UNIVERSITY   OF   CALIFORNIA    PUBLICATIONS. 


COLLEGE  OF  AGRICULTURE. 


AGRICULTURAL  EXPERIMENT  STATION. 


MOSQUITO    CONTROL. 


By  H.  J.  QUAYLE. 


BULLETIN     No.     178. 

(Berkeley,  Cal.,  July,  1906.) 


W.  W.  SHANNON, 


SACRAMENTO: 

:     :     :     superintendent   state   printing. 
1906. 


BENJAMIN    IDE  WHEELER,  Ph.D.,  LL.D.,  President  of  the  University 


EXPERIMENT  STATION  STAFF. 

E.  J-  WICKSON,  M.A.,  Acting  Director  and  Horticulturist. 

E.  W.  HILGARD,  Ph.D.,  LL.D.,  Chemist. 

W.  A.  SETCHELL,  Ph.D.,  Botanist. 

ELWOOD  MEAD,  M.S.,  C.E-,  Irrigation  Engineer. 

C.  W.  WOODWORTH,  M.S.,  Entomologist. 

R.  H.  LOUGHRIDGE,  Ph.D.,  Agricultural  Geologist  and  Soil  Physicist.     (Soils  and  Alkali.)    (Ab- 

M.  E-  JAFFA,  M.S.,  Chemist.    (Foods,  Nutrition?)  [sent  on  leave.) 

G.  W.  SHAW,  M.A.,  Ph.D.,  Chemist.     (Cereals,  Oils,  Beet-Sugar.) 

GEORGE  E.  COLBY,  M.S.,  Chemist.     (Fruits,  Waters,  Insecticides) 

A.  R.  WARD,  B.S.A.,  D.V.M.,  Veterinarian  and  Bacteriologist. 

E.  W.  MAJOR,  B.Agr.,  Animal  Industry. 
RALPH  E.  SMITH,  B.S.,  Plant  Pathologist. 

F.  T.  BIOLETTI,  M.S.,  Viticultunst. 

WARREN  T.  CLARKE,  B.S.,  Assistant  Entomologist  and  Supt.  Farmers'  Institutes. 

H.  M.  HALL,  M.S.,  Assistant  Botanist. 

JOHN  S.  BURD,  B.S.,  Chemist,  in  charge  of  Fertilizer  Control. 

C.  M.  HARING,  D.V.M.,  Assistant  Veterinarian  and  Bacteriologist. 
ALBERT  M.  WEST,  B.S.,  Assistant  Plant  Pathologist. 

E-  H.  SMITH,  M.S.,  Assistant  Plant  Pathologist. 

G.  R.  STEWART,  Student  Assistant  in  Station  Laboratory. 
,  Assistant  in  Soil  Laboratory. 

RALPH  BENTON,  B.S.,  Assistant  in  Entomology. 

LUDWIG  ROSENSTEIN,  Laboratory  Assistant  in  Fertilizer  Control. 

i 

D.  L-  BUNNELL,  Clerk  to  the  Director. 


R.  E.  MANSELL,  Foreman  of  Central  Station  Grounds. 
JOHN  TUOHY,  Patron, 


,  Foreman, 


Tulare  Substation,  Tulare. 


J.  W.  MILLS,  Pomona,  in  charge  Cooperative  Experiments  in  Southern  California. 

J.  W.  ROPER,  Patron, 

>      University  Forestry  Station,  Chico. 
E.  C.  MILLER  In  charge 


in,      ) 


ROY  JONES,  Patron, 

I     University  Forestry  Station,  Santa  Monica. 
N.  D.  INGHAM,  Foremai 

VINCENT  J.  HUNTLEY,  Foreman  of  California  Poultry  Experiment  Station,  Petaluma. 


The  Station  publications  (Reports  and  Bulletins),  so  long  as  avail- 
able, will  be  sent  to  any  citizen  of  the  State  on  application. 


CONTENTS. 


Page. 

INTRODUCTORY 5 

ACKNOWLEDGMENTS- 6 

COMMON  FACTS  ABOUT  MOSQUITOES 6 

MOSQUITOES  AND  DISEASE 10 

THE  PRESENT  CAMPAIGN 14 

THE  TERRITORY 14 

WHAT  WAS  DONE  ON  THE  SALT  MARSH 15 

THE  FRESH-WATER  PROBLEM 21 

SUGGESTIONS  FOR  FUTURE  WORK 25 

FISH  vs.  MOSQUITOES ._  26 

OTHER  NATURAL  ENEMIES 29 

BLUESTONE  AS  A   MOSQU1TOCIDE . 30 

EUCALYPTUS  vs.  MOSQUITOES 30 

LEGISLATION 31 

RESULTS  ACCOMPLISHED 32 

THE  SPECIES  CONCERNED— 

Ochlerotatus  lativittatus ._ 34 

Lepidoplatys  squamiger. -  _ _ 41 

Theobaldia  incidens . 45 

Culex  tarsalis  ... 48 

OTHER  SPECIES 50 

SYNOPTIC  TABLES 52 

CALIFORNIA  CULICID^-BIBLIOGRAPHY   AND  SYNONYMY 53 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/mosquitocontrol178quay 


MOSQUITO  CONTROL  WORK  IN  CALIFORNIA. 


By  H.  J.   QUAYLE. 


Introductory.— The  campaign  against  mosquitoes  recorded  in  this 
Bulletin  was  undertaken  by  the  California  Experiment  Station  at  the 
urgent  request  of  the  Burlingame  Improvement  Club.  Late  in  May, 
1904,  a  letter  was  received  by  the  entomologist  of  the  Station,  asking 
for  aid  in  relief  from  mosquitoes  in  the  vicinity  of  Burlingame,  where 
they  had  become  exceedingly  abundant  and  annoying.  This  request 
was  made  too  late  to  do  any  effective  control  for  that  season,  but  it  was 
recommended  that  a  preliminary  survey  be  made  with  a  view  to  obtain- 
ing data  for  future  work.  The  writer  was  consequently  detailed  to 
make  this  survey,  and  three  weeks  were  spent  in  the  neighborhood 
making  collections  and  locating  breeding  grounds.  In  this  study  it  was 
soon  determined  that  the  mosquito  giving  practically  all  of  the  trouble 
(estimated  at  95  per  cent)  was  a  species  that  bred  in  salt  or  brackish 
water  only,  and  that  in  any  work  looking  toward  control,  the  salt-marsh 
area  must  receive  first  consideration.  This  being  known,  the  pre- 
liminary report  made  to  the  Burlingame  Improvement  Club  gave  but 
little  encouragement,  because  of  the  extent  of  the  marsh  land  that  must 
be  included  in  the  problem.  It  was  further  stated,  however,  that  if 
they  were  considering  the  problem  in  earnest,  and  wished  to  go  to 
the  expense  necessary  to  control  this  large  breeding  ground,  the  Ex- 
periment Station  would  be  glad  to  outline  a  plan  of  campaign  for 
the  following  season. 

Nothing  more  was  heard  about  the  matter  until  early  in  August, 
when,  owing  to  the  excessive  abundance  of  mosquitoes,  due  to  the 
emergence  of  a  brood  on  the  marsh,  Mr.  G.  A.  Pope,  president  of 
the  Burlingame  Improvement  Club,  wrote  again  to  the  Station,  ask- 
ing if  it  would  not  be  possible  to  at  least  mitigate  the  nuisance  im- 
mediately. In  reply  to  this  communication  it  was  stated  that  the 
mosquitoes  now  flying  about  would  remain  well  up  to  the  close  of 
the  season,  and  that  the  prevention  of  other  broods  from  appearing 
would  not  lessen  the  numbers  to  any  perceptible  degree.  It  was  pro- 
posed, however,  that  a  class  of  students  from  the  University  make 
weekly  trips  to  the  territory,  in  order  to  secure  more  data  as  a 
roundation  for  the  practical  control  work.  Such  a  course  was,  there- 
fore, announced  in  the  University  curriculum,  and  some  half  dozen 


6  UNIVERSITY  OP   CALIFORNIA— EXPERIMENT   STATION. 

advanced  students  in  entomology  thus  availed  themselves  of  the  op- 
portunity of  getting  acquainted  with  the  practical  side  of  the  subject. 

In  the  middle  of  February,  1905,  the  writer  met  with  the  members 
of  the  Burlingame  Improvement  Club  in  San  Francisco  and  outlined 
a  plan  of  campaign.  In  this  plan  it  was  recommended  that,  in  so  far 
as  possible,  the  work  be  of  a  permanent  nature,  such  as  ditching  and 
filling  in,  this  to  be  supplemented  by  oiling,  where  it  was  necessary  to 
keep  ahead  of  the  developing  mosquitoes,  or  where  permanent  work 
would  be  done  only  at  great  expense.  After  estimating  the  amount 
of  ditching  necessary  on  the  marsh,  the  expense  of  repairing  dikes  and 
the  use  of  oil  and  other  materials  necessary,  the  minimum  expendi- 
ture was  placed  at  $2,000.  When  this  was  submitted  to  the  Club  it 
received  a  unanimous  indorsement,  and  the  consensus  of  opinion  was 
that  the  mosquito  must  go  at  any  cost.  Having  this  assurance  of  moral 
and  financial  support  we  were  ready  to  begin  the  active  work  of  the 
campaign  at  once,  and  a  gang  of  men  was  immediately  set  to  work. 

The  chief  aim  of  the  campaign  was  to  get  results  in  the  control 
work,  and  demonstrate  to  the  people  of  the  State  in  general,  and  of 
this  territory  in  particular,  that  the  mosquito  nuisance  can  be  checked 
if  the  people  only  take  up  the  problem  in  sufficient  earnestness.  The 
funds  were  contributed  with  this  end  in  view,  and,  consequently,  prac- 
tically all  of  our  energies  were  taken  up  with  this  phase  of  the  prob- 
lem, and  there  was  little  time  left  for  a  purely  biological  study,  such 
as  we  would  liked  to  have  carried  on.  However,  many  interesting 
things  were  observed,  and  some  additions  made  to  our  knowledge  of 
the  species  concerned. 

Acknowledgments. — An  expression  of  thanks  is  extended  to  the 
members  of  the  Burlingame  Improvement  Club,  who  made  the  cam- 
paign possible,  and  particularly  to  their  president,  Mr.  G.  A.  Pope, 
whose  encouragement  and  cooperation  were  greatly  appreciated. 
Thanks  are  also  due  the  trustees  and  principal  of  the  San  Mateo  High 
School  for  allowing  us  the  use  of  a  room  in  the  high  school  building 
for  laboratory  purposes,  and  to  Attorney  George  C.  Ross,  of  Redwood 
City,  for  the  use  of  a  room  in  his  building  at  Millbrae  for  head- 
quarters  of  the  campaign  in  that  section.  Mention  should  be  made  also 
of  the  Trustees  of  the  city  of  San  Mateo  and  the  Board  of  Super- 
visors of  the  county  for  their  part  in  the  cause  in  the  way  of  legislation. 

SOME    COMMON   FACTS   ABOUT    MOSQUITOES. 

Since  the  present  Bulletin  is  the  first  publication  issued  by  the 
Experiment  Station  on  the  subject  of  mosquitoes,  and  in  order  to 
correct  some  erroneous  ideas  which  prevail  over  the  State  regarding, 
particularly,  their  breeding  places  and  habits,  an  account  of  the  better 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA.  7 

known  facts,  modified  to  apply  to  conditions  in  the  bay  region  of  the 
State,  is  inserted  here. 

Life  History.— The  eggs  of  mosquitoes  are  laid,  either  singly  or  in  raft- 
like masses,  in  quiet  water,  which  may  be  either  fresh  or  salt,  or  in  the 
mud  of  drying  pools.  This  latter  situation,  so  far  as  observed,  is  selected 
only  by  the  salt-marsh  species,  and  was  first  observed  by  Professor 
Smith,  of  New  Jersey,  for  the  common  salt-marsh  species  (Ochlerotatus 
sollicitans)  of  the  Atlantic  Coast,  and  was  also  determined  by  us  for 
our  common  species  (0.  lativittatus)  about  San  Francisco  Bay.  The 
eggs  hatch,  in  from  one  to  four  days,  depending  upon  the  species  and 
temperature  conditions,  and  there  emerges  from  the  egg  an  active 
creature  popularly  known  as  a  "wriggler,"  which  is  the  larval  stage 
of  the  insect. 

This  larval  stage  is  passed  in  wTater,  and  not  in  alfalfa  fields,  freshly 
sprinkled  lawns,  cypress  hedges,  and  other  equally  impossible  places, 
as  has  been  strongly  maintained  by  many  people  whom  we  have  met 
with  during  the  past  year  or  two,  among  whom  may  be  mentioned  a 
well-known  Horticultural  Commissioner,  whose  office  is  supposed  to 
require  a  certain  knowledge  of  insects.  Mosquitoes  occurring  in  alfalfa 
fields  or  recently  sprinkled  lawns  may  be  accounted  for  from  the  fact 
that  they  are  attracted  to  moisture,  but  that  they  actually  breed  in 
some 'water,  possibly  in  the  immediate  neighborhood;  in  the  case  of 
the  alfalfa  field  it  may  be  in  the  irrigation  ditch.  They  gather  about 
cypress  hedges  in  order  to  seek  shelter  from  the  strong  winds.  To 
one  who  is  familiar  with  the  anatomy  of  the  young  mosquito  it  is  diffi- 
cult to  conceive  of  them  occurring  anywhere  but  in  water.  The  mouth 
parts  of  the  larval  mosquito  consist  of  a  pair  of  hair-like  brushes,  which 
are  kept  in  motion  most  of  the  time,  and  their  action  is  such  that  a 
current  of  water,  with  all  the  small  organisms  that  go  with  it,  is 
directed  to  the  mouth  and  thus  the  larva  gets  its  supply  of  food.  Al- 
though living  in  the  water  the  larva  is  air-breathing,  and  obtains  this 
air  by  projecting  a  tube,  situated  on  the  posterior  end  of  the  body, 
just  above  the  surface  film.  Failure  to  obtain  this  supply  of  air  very 
soon  results  in  the  insect's  drowning,  and  this  largely  explains  the 
effect  of  an  insecticide,  such  as  an  oil,  upon  the  surface  of  the  water. 
The  oil  forms  an  air-proof  film  over  the  surface  which  the  larva  can 
not  penetrate  with  its  breathing  tube.  Thus  the  air  supply  is  shut  off; 
besides,  the  oil  itself  undoubtedly  acts  directly  upon  the  larva,  as  may 
be  inferred  from  the  twisting  of  its  body  when  it  strikes  the  oil. 

After  molting  or  shedding  its  skin  two  or  three  times  we  have  a 
creature  which  looks  like  a  larva  coiled  up  at  one  end,  and  in  this 
stage  it  is  the  pupa.  Now,  instead  of  breathing  through  a  single  respir- 
atory tube  at  the  end  of  the  body,  it  breathes  by  means  of  two  respir- 


8  UNIVERSITY   OF    CALIFORNIA  — EXPERIMENT   STATION. 

atory  siphons  on  the  thorax.  It  may  still  be  called  a  wriggler  in 
this  stage,  since  it  is  capable  of  movement  and  will  rapidly  dart  away 
from  its  characteristic  position  at  the  surface  of  the  water  when  dis- 
turbed. Locomotion  in  this  stage  is  accomplished  by  means  of  its  flex- 
ible abdomen,  which  bears  at  its  tip  a  pair  of  swimming  flaps.  The 
larval  life  of  a  mosquito  lasts  from  one  to  three  weeks,  and  the  pupal 
stage  from  two  days  to  a  week,  depending  upon  the  species  and  the 
temperature  and  food  conditions. 

The  adult  winged  mosquito  emerges  through  a  rent  in  the  skin  of 
the  pupa,  and,  after  resting  on  this  old  discarded  skin  long  enough 
to  dry  its  wings,  it  flys  away,  a  fully  developed  insect,  ready  to  begin 
its  active  warfare  upon  man  and  other  warm-blooded  animals.  It  is 
only  the  female,  however,  that  seeks  this  source  for  its  food  supply, 
the  males  not  having  developed  a  thirst  for  blood,  and  subsisting  largely 
upon  the  juices  of  plants.  The  length  of  life  of  the  adult  winged  mos- 
quito can  at  best  only  be  approximated,  but  observations  made  during 
the  season  just  past  show  that  they  may  live  for  three  months,  al- 
though the  great  mass  of  them  die  in  the  course  of  three  or  four  weeks. 
The  entire  life  cycle,  therefore,  may  vary  from  two  or  three  weeks  to  as 
many  months. 

The  number  of  broods  appearing  in  a  season  depends  upon  the 
species  and  the  climate;  the  marsh  mosquito,  Ochlerotatus  lativittatus, 
in  the  San  Francisco  Bay  region,  was  observed  to  produce  a  brood  each 
month  from  February  to  September  inclusive,  making  eight  in  all, 
while  the  common  fresh-water  form,  Theobaldia  incidens,  breeds  practi- 
cally the  year  round  in  this  region.  Mosquitoes  may  pass  the  winter  in 
either  of  the  three  stages— egg,  larva,  or  adult.  The  marsh  species, 
0.  lativittatus,  passes  the  winter  in  the  egg  state,  while  other  species 
of  the  sub-family  Culicinae  and  one  of  Anopheles  were  found  hiber- 
nating. 

Where  Mosquitoes  Breed.  — In  brief,  mosquitoes  will  breed  in  any 
quiet  water;  the  water  may  be  very  foul  or  it  may  be  very  clean. 
The}7  are  not  found  in  large  bodies  of  water,  except,  possibly,  near  the 
edges,  but  the  small,  insignificant  pools  are  their  favorite  haunts.  Not 
a  few  people  at  Burlingame  and  Millbrae  believed  their  mosquitoes 
came  from  the  Spring  Valley  lakes,  and  it  was  not  until  the  present 
campaign  was  carried  well  into  the  summer  that  they  were  convinced 
of  their  error.  On  account  of  the  continual  rippling  of  the  water  in 
these  large  bodies,  and  also  because  of  the  fact  that  fish  are  usually 
present,  no  mosquitoes  are  found,  barring  the  borders,  in  such  situa- 
tions. A  very  general  breeding  ground  in  the  bay  region  of  California 
is  furnished  by  the  numerous  creeks  from  the  hills,  drying  up  with  the 
cessation  of  rains  and  forming  pockets  and  other  stagnant  pools  along 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA.  9 

their  course.  Small  containers  of  water,  such  as  pails,  barrels,  or  even 
a  tin  can,  may  also  furnish  sufficient  annoyance  for  a  family  during  a 
season. 

Migrations.— People  living  in  the  vicinity  of  salt  marshes  must  look 
beyond  their  immediate  neighborhood,  and  decide  whether  or  not  a 
marsh  at  a  considerable  distance  away  is  not  furnishing  them  with 
their  supply  of  mosquitoes.  This  makes  the  problem  of  control  work 
much  more  difficult  in  such  regions,  and  little  can  be  done  without 
a  general  movement  in  which  the  whole  community  participates.  The 
salt-marsh  mosquito  in  New  Jersey  has  been  known  to  migrate  thirty 
or  forty  miles,  and  we  have  observed  our  California  species  at  least 
ten  miles  from  any  breeding  ground.  The  wind  is  an  important  factor 
here,  and  usually  such  migrations  occur  only  with  a  favorable  wind. 
For  example,  the  Burlingame  mosquitoes  came  from  the  marsh  to  the 
north,  from  where  the  wind  could  easily  carry  them  into  the  district. 

Collecting  and  Studying  Mosquitoes.— The  collecting  of  larvae  and 
pupae  is  best  accomplished  by  means  of  a  small  net,  as  shown  in  Fig. 
1.  This  net  is  made  by  bending  a  heavy  wire  in  the  form  as  shown, 
the  ends  being  soldered  into  a  ferrule  to  re- 
ceive the  handle,  and  over  this  frame  is  sol- 
dered a  wire  screen  of  fine  mesh.  It  is  an 
advantage  to  have  the  wire  tight  for  the  easy 
transfer  of  the  materials  to  the  vials.  A. net 
measuring  four  or  five  inches  across  was 
found  to  be  the  most  convenient  size,  a  larger 

.     .  _  FIG.  1.    Insect  net. 

net  not  being  easy  to  manipulate  among  vege- 
tation or  in  small  pools  or  cracks.  To  transfer  the  specimens  into 
vials  a  small  camel 's-hair  brush  will  be  found  most  convenient,  or,  in 
the  absence  of  this,  the  mouth  of  the  vial  may  be  placed  so  as  to 
inclose  them  and  the  insects  washed  in  by  the  water  of  the  vial.  Eight- 
dram  homo  vials  are  suitable  for  the  larvae,  and  these  should  not  con- 
tain too  much  water,  and  should  be  brought  to  the  laboratory  with  as 
little  jarring  as  possible,  else  the  specimens  will  drown.  A  few  may 
be  reared  in  these  vials,  but  if  there  is  a  quantity,  or  the  specimens  are 
newly  hatched,  they  should  be  transferred  to  larger  vessels  where  there 
is  a  greater  food  supply. 

For  preserving  larvae  for  future  study  they  should  be  killed  with 
hot  water  and  run  through  the  grades  of  alcohol  and  finally  preserved 
in  95  per  cent  alcohol.  A  mixture  which  was  found  to  preserve  the 
form  and  color  well  consisted  of  5  per  cent  of  glycerine,  2  per  cent  of 
formalin,  and  water.  Larval  skins  should  be  preserved  for  studying 
the  chitinous  parts,  or  in  the  absence  of  these,  specimens  may  be 
treated  in  weak  potash  solution. 


10 


UNIVERSITY   OF    CALIFORNIA  — EXPERIMENT   STATION. 


The  adults  may  be  collected  by  means  of  vials,  which  are  placed 
over  the  specimens  as  they  are  resting  upon  the  hands  or  clothing,  or 
by  means  of  the  ordinary  insect  net.  The  latter  way  should  be  used 
especially  for  collecting  males  in  the  vicinity  of  the  breeding  ground. 
Of  course,  the  most  preferable  means  of  securing  the  adults  is  to  rear 
them  from  the  larvae.  They  should  be  mounted  immediately  after 
being  taken,  either  on  small  paper  triangles  or  with  very  fine  pins. 


FIG.  2.     Anopheles. 


MOSQUITOES  AND  DISEASE. 

It  is  now  a  well-established  fact  that  several  species  of  mosquitoes 
are  the  active  disseminating  agents  of  at  least  two  or  three  kinds  of 
contagious  disease.  Space  here  will  not  permit  of  the  many  interesting 
facts,  or  the  conclusive  proof  by  experimentation  that  has  resulted  from 
investigations  carried  on  along  this  line  in  recent  years;  but  readers 
who  are  interested  in  more  than  a  mere  statement  of  facts  are  referred 
to  special  articles  dealing  with  insects  in  their  connection  with  disease. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA. 


11 


Malaria  and  Mosquitoes.— The  old  theory  that  malaria  was  caused  by 
miasma  or  swampy  air  has  now  given  way  to  the  more  modern  and 
experimentally  proved  fact  that  mosquitoes  belonging  to  the  particular 
genus  Anopheles  are  responsible  for  the  spread  of  this  disease.  The 
Anopheles  mosquito  detains  the  malarial  protozoan  from  the  blood  of  a 
malarial  patient,  which,  after  going  through  a  course  of  development 
within  the  body  of  the  mosquito,  is  ready  to  be  transferred  to  the 
blood  of  the  next  person  bitten  by  the  mosquito. 

This  genus  of  mosquitoes  should  be  known  by  every  one,  and  Figs. 


FIG.  3.    Theobaldia. 

2  and  3  should  make  this  distinction  clear.  The  Anopheles,  it  will  be 
•seen,  has  spotted  wings,  but  this  is  not  a  character  peculiar  to  the 
genus,  since  the  commonest  species  of  Theobaldia,  here  figured  from 
the  bay  region  of  California,  has  spotted  wings.  The  three  appendages 
projecting  from  the  head  of  Anopheles  are  entirely  characteristic,  while 
in  the  Culicinae  there  appears  to  be  but  one  long  process,  the  beak. 
These,  which  occur  on  either  side  of  the  beak  in  Anopheles,  are  the 
palpi,  and  are  always  as  long  as  the  beak,  but  in  the  Culicinae  they  are 
short  and  inconspicuous  in  the  females.  The  males  are  distinguished 
by  their  bushy  antennas,  but  since  these  do  no  biting,  it  is  important  to 
know  only  the  distinguishing  characters  of  the  females,  as  shown  in  the 
figures.  The  figures  also  show  the  characteristic  resting  positions  of 
the  two  genera. 


12 


UNIVERSITY   OP    CALIFORNIA— EXPERIMENT   STATION. 


In  Figs.  4  and  5  the  normal  position  of  the  larva  of  a  Culicinae  and 
Anopheles  is  shown — Theobaldia  with  its  long  breathing  tube  and  hang- 


FIG.  4.     Anopheles  larva. 


FIG.  5.    Theobaldia  larva 


ing  at  an  angle,  while  the  Anopheles  has  a  short  breathing  tube  and  is 
parallel  with  the  surface  of  the  water,  and  is  a  surface  feeder,  while 
the  Culicinae  obtains  its  food  from  beneath  the  surface. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA. 


13 


There  are  three  species  of  Anopheles  in  California,  but  only  one, 
Anopheles  maculipennis ,  has  been  actually  demonstrated  to  transmit 
the  malaria  protozoan.  The  other  species,  however,  are  likely  to  do  so, 
and  until  they  are  proven  incapable  of  acting  as  a  host  for  the  para- 
site they  should  be  regarded  with  some  respect. 

Mosquitoes  and  Filariasis.— The  dreaded  and  incurable  disease  known 
as  filariasis,  which  is  confined  mostly  to  the  tropics,  is  now  known  to 
be  transmitted  from  one  patient  to  another  by  mosquitoes.  This  dis- 
ease manifests  itself  in  several  forms ;  one  of  the  most  common,  known 
as  elephantiasis,  attacks  as  many  as  a  third  of  the  natives  in  some  of 
the  tropical  countries,  and  invariably  proves  fatal. 

Mosquitoes  and  Yellow  Fever. — Yellow  fever  was,  up  to  the  last  few 
years,  thought  to  be  spread  by  fomites  or  contact  with  clothing  or  other 


FIG.  6.    Pupa  of  a  mosquito  (Theobaldia). 

belongings  of  fever  patients;  but  the  investigations  of  our  United 
States  army  surgeons  in  Cuba  in  1900  overthrew  this  conception  re- 
garding the  spread  of  the  disease,  and  proved  by  actual  experiment 
that  the  disease  was  transmitted  by  a  certain  species  of  mosquito 
(Stegomyia  fasciata).  As  a  result  of  this  knowledge  the  disease  has 
been  practically  stamped  out  of  many  places  where  it  was  formerly 
prevalent,  among  which  may  be  mentioned  Havana,  in  Cuba,  where  it 
is  no  longer  dreaded  in  the  degree  that  it  was  formerly. 

Still  more  recent  history  has  been  made  in  New  Orleans  during  the 
past  summer,  and  while  there  were  a  good  many  deaths,  the  disease 
did  not  spread  or  cause  the  alarm  that  former  epidemics  have  occa- 
sioned, for  the  reason  that  the  etiology  of  the  disease  was  better  un- 
derstood. According  to  statistics  compiled  by  Dr.  J.  H.  White,  of 
the  United  States  Public  Health  and  Marine  Hospital  Service,  the 
total  number  of  known  deaths  in  the  entire  South  up  to  October  15th 


14  UNIVERSITY  OF   CALIFORNIA — EXPERIMENT   STATION. 

was  924.  When  it  is  understood  that  there  was  a  total  of  616  dead 
and  prostrated  victims  (according  to  the  Interstate  Medical  Journal) 
by  the  time  the  work  of  eradication  was  well  under  way,  the  results 
are  remarkable.  In  a  letter  just  received  from  Dr.  L.  0.  Howard,  of 
the  Department  at  Washington,  he  has  assured  us  that  all  of  the 
preventive  work  carried  on  there  by  the  State  and  city  authorities 
and  of  the  United  States  Public  Health  and  Marine  Hospital  Service 
was  directed  solely  against  the  yellow-fever  mosquito.  The  work  in- 
cluded the  screening  of  tanks,  treating  the  gutters  with  oil,  and  other 
measures  looking  toward  the  abolition  of  the  breeding  places ;  the  fumi- 
gation of  houses  containing  fever  patients  in  order  to  destroy  the  adult 
mosquito,  and  the  protection  of  patients  by  netting  in  order  that  the 
mosquito  should  have  no  opportunity  to  bite  and  later  convey  the  disease. 

THE  PRESENT  CAMPAIGN. 

The  Territory. — The  territory  involved  in  the  present  campaign  is 
included  in  the  upper  portion  of  the  San  Francisco  peninsula,  ex- 
tending from  South  San  Francisco  on  the  north  to  San  Mateo  on  the 
south,  a  distance  of  about  10  miles.  The  average  width  of  the  peninsula 
here  is  10  or  15  miles.  Extending  midway  between  ocean  and  bay  are 
two  parallel  chains  of  hills,  the  one  on  the  bay  side  averaging  500  or 
600  feet  above  the  sea,  while  the  chain  on  the  ocean  side  attains  a 
height  of  2,000  feet  at  the  south  and  gradually  decreases  toward  the 
north  to  100  or  200  feet.  The  streams  rising  in  these  hills  flow  rapidly, 
either  into  the  bay  or  ocean,  or  into  the  chain  of  lakes  which  has  been 
made  artificially  between  the  hills,  and  is  the  source  of  San  Francisco's 
water  supply.  Beginning  near  South  San  Francisco,  on  the  bay  side, 
and  extending  well  across  the  peninsula,  about  parallel  with  the  other 
chains,  is  a  ridge  of  1,000  to  1,300  feet,  which  is  known  as  the  San 
Bruno  Mountains.  This,  together  with  the  other  two  ridges  (see  map), 
incloses  a  low  area  or  depression  not  more  than  200  feet  in  elevation, 
and  it  is  through  this  draw  that  many  of  the  winds  come  from  the 
ocean,  and  are  diverted  by  the  San  Bruno  Mountains  toward  the  south- 
ward along  the  bay  shore.  In  addition  to  this  the  winds  entering  the 
Golden  Gate  are  spread  to  the  north  and  south  along  the  bay,  and  it 
is  from  these  two  sources  that  most  of  the  winds  of  the  territory  find 
their  way  from  the  ocean.  Because  of  this  prevailing  direction  of  the 
wind,  the  troublesome  area  on  the  marshes  will  lie  largely  to  the  north- 
ward of  a  mosquito-infested  district.  It  was  on  this  basis  of  winds  that 
we  came  to  the  conclusion  in  the  present  campaign  that  the  control  work 
should  be  done  from  San  Mateo  northward,  and  little  attention  paid  to 
the  territory  to  the  south;  and  the  results  have  fully  confirmed  this 
conclusion. 


F 


^s 


8. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA.  15 

The  salt-marsh  area  included  in  this  campaign  consists  of  a  narrow 
strip  along  the  San  Francisco  bay  shore,  varying  from  %  to  2  miles  in 
width,  and  10  miles  long,  or  from  San  Mateo  to  South  San  Francisco. 
No  part  of  this  area  is  continually  covered  with  water,  and  it  is  all 
above  the  lowest  high  tide.  The  higher  tides,  however,  particularly 
those  accompanying  full  moon,  almost  completely  submerge  the  area. 
Extending  from  opposite  Millbrae  to  the  south,  along  the  bay,  is  a 
diked  area  of  500  or  600  acres.  This  dike  was  built  about  fifteen  years 
ago,  and,  excepting  for  a  year  or  two  after  completion,  has  been 
neglected,  and  consequently  in  very  poor  repair. 

Extending  over  the  entire  marsh  area  is  a  complete  network  of 
tidal  creeks,  which  wind  about  in  all  directions,  and  thus  furnish  a  rapid 
drainage  during  low  water.  This  fact  also  greatly  simplifies  the  drain- 
age problem,  since  no  long  ditches  need  be  cut.  The  vegetation  on  the 
marsh  land  consists  of  the  common  pickleweed  (Salicornia  ambigua) , 
which  is  the  characteristic  plant,  and  the  finer  salt-grass  (Distichlis 
spicata),  which  borders  the  pools  and  tidal  creeks.  There  are  no 
tules  or  large  rushes  on  this  marsh,  since  there  is  no  part  of  it  that  is 
more  or  less  continuously  submerged  with  water. 

What  Was  Done  on  the  Marsh. — The  actual  work  of  control  was 
commenced  February  27th,  when  a  gang  of  men  was  started  to  work  at 
ditching  on  the  salt  marsh.  This  work  was  started  near  the  Blackhawk 
dairy,  where  the  marshes  begin  north  of  Burlingame,  it  being  the  in- 
tention to  work  northward  toward  San  Bruno,  and  make  the  work 
permanent  as  far  as  we  would  be  able  to  go  in  a  single  season.  How- 
ever, the  work  went  rapidly  and  the  troublesome  areas  north  of  Mill- 
brae were  not  so  numerous  as  was  figured,  and  consequently  practically 
the  whole  area  was  covered  during  the  past  season. 

The  ditching  in  the  Blackhawk  area  consisted  in  connecting  the  pools 
and  areas  of  standing  water  with  the  tidal  creeks  in  order  that  they 
might  drain  more  rapidly  and  before  a  brood  of  mosquitoes  would  have 
time  to  develop.  The  largest  of  these  ditches  were  12  inches  wide  and 
about  15  inches  deep,  and  these  served  as  main  channels  into  which 
smaller  laterals  were  cut.  These  laterals,  and,  indeed,  the  greater  part 
of  all  of  the  ditches,  were  but  one  spade  wide,  and  one  or  two  spades 
deep,  according  to  the  depth  of  the  pool  to  be  drained.  Only  where 
the  pools  were  very  large  and  a  great  quantity  of  water  to  run  off  in 
a  short  time  was  it  necessary  to  make  larger  ditches.  By  "a  spade" 
here  is  meant  the  common  California  spade,  which  is  about  6  inches 
wide  and  10  inches  high.  The  Eastern  drain  spade  has  not  yet  found 
its  way  to  California;  undoubtedly  it  would  be  preferable  for  the 
deeper  ditches  in  this  kind  of  work.  In  addition  to  the  well-defined 
pools  there  was  a  considerable  area  in  the  Blackhawk  region  which 


r.' 


t^!#.C 


*      >«*^       • 


w,  \ 


FIG.  9.     One  of  the  main  laterals,  into  which  were  cut  smaller  ditches. 


FIG.  10.     A  large  tidal  creek  in  the  diked  area,  almost  dry. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA. 


17 


was  covered  with  but  a  few  inches  of  water  for  a  considerable  time 
after  each  high  tide,  and  before  the  rains  ceased  in  the  spring  water 
stood  over  this  area  almost  continuously.  Such  areas  had  to  be  treated 
by  making  a  number  of  parallel  ditches  from  50  to  75  feet  apart,  in 
order  to  permit  of  sufficiently  rapid  drainage.  Rather  extensive  ditch- 
ing was  done  here  to  make  the  area  safe  while  the  rains  were  still  con- 
tinuing, while  later  in  the  season,  when  the  rains  ceased,  it  would  have 


FIG   11.    The  lower  gate  on  the  dike,  showing  automatic  gate  in  front  of  old  one 

manipulated  by  screws. 

been  safe  with  much  less  ditching.  Small  pools  that  were  far  from 
tidal  creeks  were  made  safe  by  filling  in  rather  than  draining.  The 
size  of  the  pool,  and  the  length  of  ditch  necessary  to  drain,  will  deter- 
mine which  of  the  methods  is  to  be  followed.  In  this  way  the  marsh 
area  was  gone  over,  doing  away  with  all  the  places  where  larvae  were 
found  or  were  likely  to  be  found,  for  a  distance  of  about  a  mile  along 
the  bay  northward,  where  the  diked  area  was  met  with. 

This  part   of  the  marsh  presented   a  more   difficult  problem.      The 
2-Bul  178 


18  UNIVERSITY   OF   CALIFORNIA— EXPERIMENT  STATION. 

dike,  having  been  neglected  for  ten  or  twelve  years,  was  in  poor  con- 
dition, and  there  were  several  breaks  in  the  upper  end  near  Millbrae. 
The  gates  were  not  in  working  order,  and  their  floors  were  too  high  to 
drain  the  area  inclosed. 

The  breaks  in  the  dike  at  the  upper  end  permitted  the  water  to  back 
up  at  the  opposite  side,  and  this,  together  with  the  fresh  water  from 
the  hills,  kept  the  water  level,  at  almost  high  tide,  over  a  large  part  of 
the  area.  To  make  matters  worse,  the  dike,  just  after  it  was  built,  was 
in  effective  operation  just  long  enough  to  thoroughly  dry  the  ground 
and  cause  it  to  crack.  These  creeks,  which  are  4  or  5  inches  wide  and 
2  or  3  feet  deep,  still  exist,  forming  a  complete  network  over  most  of 
the  area.  Mosquitoes  were  found  breeding  in  this  area,  and  it  was  next 
to  impossible  to  get  over  the  ground,  even  with  waders.  A  consider- 
able part  of  the  area  was  submerged  to  the  depth  of  a  foot  or  more, 
thus  concealing  from  view  the  cracks  and  tidal  creeks,  which  one  was 
likely  to  fall  into  at  any  step,  and  which  made  any  attempt  at  rapid 
progress  somewhat  discouraging. 

It  was  at  once  evident,  under  these  conditions,  that  if  the  area  was 
to  be  controlled,  the  dike  must  be  either  cut  through  in  a  number  of 
places  in  order  to  allow  a  freer  circulation  of  water,  or  the  breaks  must 
be  repaired  and  the  gates  put  in  operation,  and  the  water  kept  out. 
The  latter  scheme  was  the  one  followed,  because  it  would  be  possible  to 
make  the  area  thoroughly  dry,  and  thus  the  results  would  be  more 
certain.  In  attempting  to  operate  the  gates  we  were  made  to  appreciate 
the  effect  of  a  ten  or  twelve  years'  coating  of  rust  on  the  large  screws 
by  which  the  gates  were  manipulated.  After  the  gates  were  put  in 
operation  the  breaks  in  the  dike  were  repaired  and  the  weak  places 
strengthened.  The  largest  break  repaired  was  immediately  joining 
the  upper  gate.  This  was  30  feet  wide,  and  by  the  action  of  the  water 
had  worn  down  so  that  at  high  tide  there  was  a  depth  of  10  feet  of  water. 
A  double  wall  of  sheet  piling  about  6  feet  apart  was  sunk  here  and  the 
space  between  filled  in  with  earth.  The  other  breaks  were  repaired  by 
sinking  a  single  wall  of  sheet  piling  in  the  center  and  filling  in  on  both 
sides  with  dirt. 

After  these  repairs  were  completed  the  gates  were  operated,  opened 
at  low  tide  and  closed  at  high  tide,  for  a  week,  but  at  the  end  of  this 
time  there  was  still  much  water  in  the  area,  because  the  gate  floors  were 
not  low  enough  to  lower  the  water  level  sufficiently.  This  made  it 
necessary  to  lower  the  gate  floors  and  add  an  extension  to  the  gates 
to  reach  the  lower  level.  This  being  done  the  gates  were  again  operated 
for  several  days,  but  it  was  found  that,  due  to  seepage  of  water  through 
the  dike  in  many  places,  hand  operating  would  have  to  be  kept  up 
almost  indefinitely.     It  was,  therefore,  necessary  to  replace  these  old- 


*<FIG  12.    Upper  gate  on  dike.    On  right,  double  wall  of  sheet  piling  shows  manner  of 

repairing  large  breaks. 


FIG.  13.    Upper  gate  on  the  dike.    Beam  in  center  shows  former  level  of  floor.    Repair  work  on  left. 


20 


UNIVERSITY   OF   CALIFORNIA  — EXPERIMENT   STATION. 


style  gates,  operated  by  hand,  by  automatic  ones,  and  these  were, 
consequently,  put  in  at  both  the  upper  and  lower  gates,  and  the  floors 
lowered  32  and  20  inches  respectively.  These  gates  were  made  to 
swing  on  an  axle  at  the  top,  the  lower  end  being  free  and  easily  moved 
by  the  pressure  of  the  water,  so  that  at  low  tide  it  was  opened  by  the 
pressure  of  water  on  the  inside,  and  closed  as  the  water  from  the  high 
tide  rose  on  the  outside. 

The  tidal  creek  which  served  as  an  outlet  for  the  lower  gate  had 
become  filled  in  to  a  depth  of  2  or  3  feet  during  the  period  the  gate 
was  closed,  and  this  was  cleaned  out  for  300  or  400  yards  toward  the 
bay  in  order  to  drain  out  the  area  inclosed  by  the  dike. 


FIG.  14.     A  typical  hand-made  ditch  on  the  marsh. 

With  this  work  done  upon  the  dike  the  area  inclosed  by  it  was  treated 
in  much  the  same  way  as  that  outside,  except  that  the  network  of  cracks, 
already  mentioned,  had  to  be  filled  in  in  many  places,  and  several  of 
the  tidal  creeks  deepened.  The  reward  for  all  this  work  came  later 
in  the  season  when  the  area  was  changed  from  a  veritable  breeding 
ground  to  the  safest  portion  of  the  marsh.  Indeed,  this  area  was  the 
key  to  the  situation,  and  the  excessive  abundance  of  mosquitoes  in  this 
particular  territory  was  without  doubt  due  to  this  extensive  breeding 
ground. 

It  is  appropriate  to  mention  here  the  connection  of  this  work  with 
the  reclamation  of  marsh  lands.  This  tract  of  500  or  600  acres,  which 
had  been  useful  only  for  duck-hunting,  is  now  thoroughly  dry  and 
could  be  put  to  agricultural  uses  at  very  little  additional  expense.    Such 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA. 


21 


work  has  already  been  extensively  taken  up  on  the  marshes  below  San 
Mateo,  and  it  has  been  found  that  a  good  crop  of  grain  can  be  raised  on 
such  land  in  the  second  year  of  its  cultivation..  It  is  safe  to  predict 
that  all  the  marsh  land  involved  in  the  present  campaign  will  be  under 
cultivation  before  many  years,  and  because  of  its  proximity  to  the 
metropolis  of  the  coast  should  be  very  valuable. 

Besides  the  marshes  already  mentioned,  permanent  control  work  was 
done  on  the  marsh  about  Millbrae  and  northward  to  San  Bruno,  and 
also  some  drainage  work  at  Coyote  Point,  opposite  San  Mateo.  The 
work  at  these  places  was  much  the  same  as  that  already  described,  and 
further  details  are  unnecessary. 


FIG.  15.    A  large  fresh-water  pond.    A  favorite  place  for  Anopheles. 

In  addition  to  this  permanent  work  there  was  some  oiling  done  on 
the  marsh  where  the  ditching  and  filling  work  were  not  rapid  enough 
to  keep  ahead  of  a  developing  brood.  The  total  amount  of  oil  applied, 
however,  did  not  exceed  400  gallons,  and  most  of  this  was  applied 
to  the  large  tidal  creeks  in  the  reclaimed  land  opposite  San  Mateo. 
The  remainder  was  applied  to  pools  where  wrigglers  appeared  after  a 
high  tide,  and,  the  brood  being  checked,  we  had  until  the  next  high 
tide  in  which  to  make  the  pools  permanently  safe. 

The  Fresh-Water  Problem. — The  fresh-water  problem  is  a  compara- 
tively easy  one  in  this  section,  because  of  the  good  drainage  toward  the 
bay,  and  because  of  the  cessation  of  rains  in  the  early  spring.  Pools 
and  creeks  that  once  become  dry  require  no  further  attention  during 


22  UNIVERSITY   OF    CALIFORNIA  — EXPERIMENT   STATION. 

the  season,  and  this  greatly  simplifies  control  work  against  fresh-water 
forms  in  arid  climates  like  that  of  California.  The  most  troublesome 
breeding  places  for  fresh-water  mosquitoes  in  the  Burlingame  section 
are  in  the  numerous  creeks  coming  down  from  the  hills.  Some  of  these 
dry  up  very  soon  after  the  rains  cease,  but  in  others  there  may  be 
standing  pools  until  late  in  the  summer.  These  pools  are  due  generally 
to  seepage  which  may  make  its  appearance  at  different  places  along  the 
course  of  the  creek. 

During  the  present  season  most  of  these  creeks  were  oiled  and  a  few 
were  drained.  Where  the  creeks  soon  become  dry  one  application  of 
oil  may  be  sufficient,  and  this  is  almost  as  satisfactory  as  draining, 
since,  owing  to  the  heavy  rains  of  winter,  and  the  swift  current,  debris 
is  lodged  in  some  places  and  holes  made  in  others,  so  that  the  creeks 
must  be  gone  over  every  season.     Moreover,  many  of  the  creek  beds 


FIG.  16.    Same  pond  after  drainage.    Outlet  in  background. 

along  a  part  of  their  course  are  in  solid  rock,  which  makes  draining 
difficult.  However,  in  spite  of  these  objections,  the  experience  this 
year  would  warrant  drainage,  especially  in  the  creeks  where  the  water 
remains  in  pools  and  pockets  for  several  months  after  the  winter  rains. 
In  addition  to  the  creeks  already  mentioned  there  are  a  few  fresh- 
water ponds  in  the  territory,  but  the  worst  one  of  these  has  been  drained. 
This  pond  was  on  the  Easton  property,  half  a  mile  north  of  the 
Burlingame  depot,  and  was  a  favorite  breeding  place  for  the  malarial 
mosquito  (Anopheles  maculipennis) .  The  owner  of  the  property 
drained  this  pond  at  his  own  expense,  which  not  only  made  useful  a 
tract  that  was  formerly  a  waste,  but  also  added  to  the  value  of  the 
land  in  the  immediate  vicinity,  which  has  since  been  subdivided  into 
residence  property,  to  say  nothing  about  the  riddance  of  the  malarial 
and  other  mosquitoes.     The  ditch  draining  this  pond  was  made  with 


FIG.  17.    Cutting  the  ditch  for  drainage  of  Easton  pond. 


FIG.  18.    Cutting  the  ditch  for  drainage  of  Easton  pond. 


24 


UNIVERSITY   OF    CALIFORNIA  —  EXPERIMENT   STATION. 


horses  and  scrapers,  and  is  12  feet  wide  at  the  top,  4  feet  at  the  bottom, 
and  from  3  to  5  feet  deep. 

A  considerable  amount  of  oiling  was  done  on  the  fresh-water  areas, 
the  permanent  work  having  been  pretty  largely  restricted  to  the  marsh 
lands.  The  oil  used  was  a  combination  of  heavy  oil  of  18  degrees 
gravity  and  light  oil  of  34  degrees  gravity,  in  the  proportion  of  four 
to  one.  This  mixture  made  an  oil  that  was  just  thin  enough  to  spray 
well  from  an  ordinary  spray  nozzle,  and  yet  was  thick  enough  to 
withstand  very  rapid  evaporation.    It  was  applied  by  means  of  a  barrel 


FIG.  19;    The  ditch  after  it  was  completed. 


pump,  where  this  could  be  used,  but  in  the  creeks  and  other  situations 
which  could  not  be  reached  by  horse  and  wagon,  the  ordinary  knapsack 
pump  was  used.  The  price  of  the  heavy  oil  at  Burlingame  was  2  cents 
a  gallon,  while  the  lighter  oil  was  2%  cents  a  gallon.  The  former  was 
obtained  from  the  Bakersfield  district,  while  the  latter  was  a  product 
of  the  Coalinga  fields.  The  number  of  applications  of  oil  depended 
somewhat  upon  the  nature  of  the  pool  and  its  exposure  to  winds,  but 
in  no  case  could  it  be  counted  as  thoroughly  effective  after  a  period  of 
four  weeks. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA. 


25 


Suggestions  for  Future  Work. — It  is,  of  course,  impossible  to  cover 
all  of  the  ground  completely  in  a  single  season,  and  while  no  breeding 
place  on  the  marsh  escaped  us  this  year,  new  ones  are  likely  to  appear 
in  the  future,  so  that  the  territory  should  be  gone  over  for  two  or  three 
years,  or  until  every  possible  breeding  place  is  rendered  safe.  The 
large  tidal  creeks  opposite  San  Mateo  harbored  mosquito  larvae  during 


FIG.  20.    Draining  in  one  of  the  typical  fresh-water  creeks  of  Burlingame. 


the  past  season,  and  are  likely  to  give  trouble  again  next  year.  Mos- 
quitoes from  this  breeding  ground,  however,  may  not  get  as  far  north 
as  Burlingame,  but  they  will  certainly  reach  San  Mateo,  which  is  just 
opposite.  There  is  also  a  small  creek  running  alongside  the  road  at  the 
Burlingame  wharf  that  should  be  attended  to  during  the  coming  season. 
This  was  oiled  during  the  past  summer,  but  it  is  troublesome  up  to 
July,  and  should  be  drained  by  putting  a  culvert  through  the  road  to 
the  bay.     In  this  culvert  should  be  built  a  self-operating  gate,  which 


26  UNIVERSITY  OF   CALIFORNIA— EXPERIMENT  STATION. 

will  allow  the  water  of  the  ditch  to  pass  out,  but  prevent  the  high  tide 
from  entering  again.  The  gates  on  the  dike  should  be  visited  occasion- 
ally to  see  that  they  are  in  working  order,  and  are  not  kept  from 
closing  by  timbers  which  are  likely  at  any  time  to  drift  in  and  lodge 
in  the  gate.  The  dike  should  also  be  inspected  for  breaks  or  weak  places, 
particularly  at  the  upper  end  opposite  Millbrae. 

On  the  fresh-water  area  all  standing  pools  which  are  formed  by  the 
late  spring  rains  should  receive  attention  by  either  oiling  or  draining. 
It  is  recommended  that  the  least  amount  of  oil  that  must  be  used  the 
better,  and  that  all  the  work  should  be  permanent,  where  it  is  at  all 
possible,  and  this  includes  practically  everything.  The  creeks  should 
be  attended  to  immediately  after  the  rains  cease  and  drained  by  either 
cleaning  out  the  creek  bed  or  filling  in  the  holes,  or  both.  Lastly, 
every  one  should  look  to  his  own  immediate  premises  and  see  that  such 
containers  of  water  as  horse-troughs,  fountains,  pails,  or  tin  cans 
are  not  furnishing  mosquitoes  for  the  neighborhood.  In  a  city,  or 
thickly  settled  residence  country  such  as  Burlingame,  community  effort 
is  essential. 

Fish  vs.  Mosquitoes. — A  part  of  the  plan  of  the  present  campaign 
included  the  carrying  out  of  some  large-scale  experiments  on  the  use  of 
fish  as  a  means  of  keeping  the  salt-marsh  mosquito  in  check.  However, 
when  the  typical  breeding  place  of  this  mosquito  was  well  understood, 
the  idea  was  soon  abandoned  as  impracticable.  Where  there  were  no 
permanent  pools,  which  were  necessary  for  the  maintenance  of  the  fish, 
there  were  no  mosquitoes;  whether  this  was  due  entirely  to  the  fish  we 
are  not  yet  ready  to  answer.  So  far  as  our  present  experience  goes  the 
salt-marsh  mosquito  {Ochlerotatus  lativittatus)  prefers  mud  to  water  in 
which  to  lay  its  eggs,  and  it  is  possible  that  the  eggs  would  not  be  laid  in 
these  permanent  pools  where  fish  are  present.  Whether  the  eggs  are  laid 
here  by  preference  of  situation  or  through  instinct  in  keeping  away 
from  the  fish  is  a  question  difficult  to  answer,  but  the  fact  remains  that 
it  is  the  exception  that  mosquitoes  are  found  in  the  salt-water  pools 
where  fish  are  present. 

But  this  is  not  all  of  the  question.  Practically  all  of  the  salt-marsh 
mosquito  larvae  in  the  present  campaign  were  in  situations  which  were 
unsuitable  for  fish,  situations  where  fish  would  perish  in  a  very  short 
time  were  they  introduced.  These  situations  are  the  pools  that  depend 
entirely  for  their  existence  upon  the  monthly  high  tide,  and  which 
dry  up  in  from  a  week  to  three  weeks  thereafter.  In  order  for  fish  to 
be  effective  here  they  would  have  to  be  introduced  after  every  high  tide, 
an  operation  which  would  be,  obviously,  impracticable.  Fish  are  con- 
sidered by  zoologists  as  being  a  rather  successful  group  in  the  struggle 
for  existence,  and  favorable  situations  for  their  development  will  usually 


9.  A 


FIG.  21.    The  oiling  outfit. 


FIG.  22.    Oiling  in  the  creeks. 


28 


UNIVERSITY   OF    CALIFORNIA  — EXPERIMENT   STATION. 


be  found  stocked  with  them.  And  so  in  the  present  territory  all  per- 
manent pools  were  pretty  well  stocked  with  fish.  Of  course  this  does 
not  preclude  the  feasibility  of  introducing  carnivorous  species  in  terri- 
tories where  they  are  not  now  predominant,  or  where  the  species  are  less 
carnivorous,  or  wholly  vegetable-feeders.  But  even  in  ponds  that  may 
contain  an  abundance  of  fish  in  the  freer  water  of  the  middle,  the 
vegetable  tangle  of  the  borders  may  be  pretty  well  stocked  with  larvae, 
where  they  breed  undisturbed  by  most  fish. 

In  a  letter  under  date  of  October  9th  from  President  Jordan,  of 
Stanford  University,  he  states  that  the  only  fish  likely  to  destroy  mos- 


FIG.  23.    Making  a  ditch  for  diverting  water,  which  formerly  spread  over  a  wide  area,  to  a 

definite  channel. 

quito  larvae  to  any  extent  in  the  San  Francisco  Bay  region,  would  be 
the  stickleback  (Gasterosteus  cataphractus) .  We  have  found  this  species 
in  the  permanent  clear-water  pools  mentioned  above,  and  it  may  be 
effective  in  keeping  the  mosquitoes  down  here;  but  this  fish,  like  all 
the  others,  does  not  reach  the  pools  where  the  mosquitoes  really  are; 
that  is,  the  temporary  pools  and  areas  formed  by  the  higher  tides. 
In  reservoirs,  or  fresh-water  ponds  artificially  formed,  or  in  fountains 
and  the  like,  or  in  the  introduction  of  carnivorous  forms  in  permanent 
pools  where  they  are  not  now  present,  fish  must  be  considered  as  a 
factor  in  mosquito  control;  but  the  mass  of  mosquito  breeding-places 
are  beyond  the  limits  of  the  typical  environment  for  fish. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA.  29 

Other  Natural  Enemies.—  Besides  fish  there  are  several  species  of 
insect  relatives  that  prey  upon  the  mosquito  in  both  its  aquatic  and 
adult  life,  and  which  are,  to  some  degree,  effective  in  keeping  the  num- 
bers within  reasonable  limits. 

The  larvae  of  dragonflies  are  carnivorous  in  habits  and  feed  upon  the 
mosquito  larvae  to  some  extent,  but,  like  most  of  the  other  natural 
enemies,  they  have  been  given  all  the  credit,  and  probably  more  than 
they  deserve.  We  have  found  mosquito  larvae  common  where  there  was 
an  abundance  of  dragonfly  larvae  in  the  pond,  but  in  such  situations 
larvae  were  never  seen  to  be  fairly  swarming,  as  they  were  in  smaller 
pools  that  were  free  from  enemies  of  all  kinds.  Where  dragonfly  larvae 
occur  it  is  not  unusual  to  also  find  fish,  since  dragonflies  require  the 
greater  part  of  the  year,  or  more,  to  go  through  their  development,  and 
hence  require  more  or  less  permanent  pools. 

The  larvae  of  the  predaceous  diving  beetles  (Dytiscidae)  were  also 
found  in  places  where  water  exists,  at  least  for  the  greater  part  of  the 
year.  These  larvae  are  voracious  eaters  and  are  more  active  than  the 
sluggish  dragonfly  larva?,  which  prefer  the  mud  or  slime  of  the  pond 
bottom,  and  are  no  doubt  more  effective,  individually,  than  the  latter; 
but  in  this  territory  they  were  never  found  to  occur  in  large  numbers. 
Bodies  of  water  that  are  favorable,  therefore,  for  the  development  of 
one  kind  of  enemy  usually  harbor  a  variety  of  enemies,  and  all  of  these 
taken  together  are  effective  in  keeping  the  numbers  of  mosquito  larvae 
from  becoming  excessive. 

There  are  several  species  of  water  bugs,  including  the  water  boatman 
(Corisiclae) ,  water  striders  (Gerridae) ,  backswimmers  (Notonectidae) , 
and  water  scorpions  (Nepidae),  that  prey  upon  mosquito  larvae,  and 
these  may  be  found  in  less  permanent  pools  than  those  already  discussed. 
A  species  of  water  boatman  (Corisa)  occurred  in  immense  numbers  in 
some  of  the  more  permanent  pools  of  the  salt  marsh,  and  in  these  pools 
no  mosquitoes  were  present.  But  there  are  too  many  conditions  enter- 
ing in  to  ascribe  the  absence  of  mosquitoes  to  this  particular  bug.  In 
several  fresh-water  pools  where  the  water  strider  was  abundant,  mos- 
quito larvae  were  seen  in  great  numbers,  and  these  water  bugs  seemed 
to  have  no  effect  on  the  number  of  larvae.  Of  course,  there  was  enough 
difference  in  the  numbers  to  make  the  supply  of  food  far  beyond  the 
demands  of  the  enemy,  but  this  too  often  occurs  with  the  slower- develop- 
ing predaceous  enemies  of  the  mosquito. 

In  general,  in  the  present  territory,  the  typical  breeding  places  for 
the  mosquito  are  not  the  typical  breeding  places  for  most  of  its  enemies. 
The  mosquito  being  more  prolific  and  the  number  of  broods  so  much 
greater  than  most  of  its  enemies,  it  persists  in  spite  of  them,  and, 
moreover,  its  distribution  extends  beyond  the  limits  of  most  of  its 
enemies,  which  are  restricted  to  more  permanent  breeding  places. 


30  UNIVERSITY   OF    CALIFORNIA  — EXPERIMENT   STATION. 

Bluestone  as  a  Mosquitocide.—A  number  of  experiments  were  carried 
on  to  test  the  value  of  copper  sulfate  for  the  destruction  of  mosquitc 
larvae,  but,  since  the  results  were  essentially  the  same  as  those  already- 
given  in  detail  in  Prof.  Smith's  New  Jersey  report  and  also  described 
by  Marlatt  in  Science  for  April  21,  1905,  only  the  general  conclusions 
suggested  by  the  experiments  will  be  given  here. 

The  value  of  bluestone  as  an  insecticide  depends  largely  upon  its 
power  of  destroying  the  small  organisms,  particularly  algae,  in  the 
water  and  thus  depriving  the  larvae  of  food.  .  Obviously,  this  will  be  of 
little  use  against  pupae  or  nearly  full-grown  larvae,  and  in  our  experi- 
ments these  invariably  developed  into  adults.  Some  large-scale  experi- 
ments were  carried  on  in  the  field,  but  these  proved  more  unsatisfactory 
than  those  carried  on  in  the  laboratory.  For  example,  a  cattle-guard 
on  the  railroad  at  Millbrae  was  fairly  swarming  with  larvae  and  pupa^ 
of  incidens,  and  copper  sulfate  was  used  at  the  rate  of  1  to  1,000,  much 
beyond  the  practicable  strength,  yet  adults  continued  to  emerge  in 
great  numbers.  Indeed,  there  was  no  effect  observed  excepting  that 
a  few  of  the  younger  larvae  were  killed.  The  water  here  was,  to  be  sure, 
very  foul  and  the  case  was  an  extreme  one,  but  in  other  clearer  pools 
the  results  were  almost  as  unsatisfactory.  Since  in  the  present  cam- 
paign it  was  our  business  to  keep  down  the  mosquitoes,  we  could  not 
afford  to  prolong  these  negative  field  tests ;  but  if  copper  sulfate  is  to  be 
used  at  all  it  should  be  applied  very  soon  after  the  eggs  hatch,  since 
it  is  too  slow  acting  to  be  of  value  against  the  later  aquatic  stages. 
Its  use  is  no  doubt  limited  to  reservoirs  or  small  bodies  of  clean  water 
where  it  will  not  be  precipitated  so  rapidly. 

Eucalyptus  vs.  Mosquitoes.— It  is  recorded  in  some  books,  and  we 
have  heard  it  stated  on  two  or  three  different  occasions  during  the  past 
year  by  physicians,  in  lecturing  on  mosquitoes  and  disease,  that  the 
eucalyptus  tree  is  effective  as  a  repellant,  and  that  where  these  trees 
exist  no  mosquitoes  will  be  found.  In  the  Burlingame  section  all  of 
the  numerous  winding  avenues  are  lined  with  eucalyptus;  there  are 
eucalyptus  along  the  highways,  and  there  are  groves  of  eucalyptus ;  yet, 
where  these  trees  are  most  abundant  it  might  be  said  that  the  mosquitoes 
are  most  numerous.  It  was  here  that  the  first  shipload  of  cuttings, 
imported  from  Australia,  were  planted,  and  the  eucalyptus  tree  is  the 
predominant  cultivated  tree  of  the  territory. 

During  the  summer  of  1904  we  captured  in  five  minutes'  sweeping, 
immediately  under  eucalyptus  trees,  a  pint  cup  full  of  mosquitoes ! 
Coyote  Point,  on  the  bay  shore,  has  long  been  known  by  the  residents 
in  the  neighborhood  as  a  famous  place  for  mosquitoes;  indeed,  the 
construction  of  a  hotel  at  this  point  which  has  been  under  contemplation 
for  some  time  is  said  to  have  been  abandoned  because  of  the  abundance 


MOSQUITO   CONTROL   WORK  IN   CALIFORNIA.  31 

of  mosquitoes,  yet  this  point  is  covered  with  eucalyptus  trees.  It  should 
not  be  understood  from  what  has  been  stated  that  the  eucalyptus  tree 
attracts  mosquitoes.  It  does  this  only  in  so  far  as  it  affords  shelter,  and 
other  trees  will  do  this  as  well,  indeed  much  better,  as  for  example  the 
Monterey  cypress  with  its  denser  foliage,  which  is  so  common  in  this 
section.  So  far  as  the  experience  in  this  locality  is  worth  anything, 
people  need  not  entertain  very  high  hopes  of  the  mosquito  pest  disap- 
pearing through  the  planting  of  the  eucalyptus  tree. 

LEGISLATION. 

The  citizens  of  the  city  of  San  Mateo  had  been  active  for  some 
years  in  fighting  the  mosquito,  but  because  of  a  lack  of  knowl- 
edge of  the  situation,  no  very  effective  work  was  done.  The  fresh- 
water areas  were  pretty  well  attended  to,  but  mosquitoes  were  still 
present,  and  these,  as  we  observed  during  the  season  of  1904,  were 
of  the  salt-marsh  variety.  The  fact  that  mosquitoes  breeding  on  the 
salt  marsh  migrate  a  considerable  distance  was  not  generally  known 
among  the  people  of  San  Mateo,  as  is  the  case  in  most  communities, 
unless  they  have  kept  in  close  touch  with  the  progress  of  mosquito- 
control  work.  During  the  past  year  quite  effective  work  was  done, 
through  voluntary  subscription,  in  keeping  in  check  the  fresh-water 
species  in  the  immediate  vicinity.  And  this,  together  with  the  work 
done  by  the  Burlingame  people,  kept  the  city  quite  free  from  mosquitoes 
during  the  past  summer. 

In  order  to  make  this  work  permanent,  and,  incidentally,  to  have 
some  check  upon  the  obstreperous  person  who  is  still  living  in  some  past 
age  regarding  his  and  his  neighbor's  welfare,  the  following  law  was 
passed ;  first  by  the  trustees  of  the  city  of  San  Mateo,  and  later  by  the 
board  of  supervisors  of  the  county. 

The  following  is  a  copy  of  that  law : 

ORDINANCE  No.  106. 

An  Ordinance  Forbidding  the  Maintenance  of  all  Places  Breeding  Mos- 
quitoes, Declaring  Such  Place  a  Nuisance  and  Providing  a  Penalty  for 
the  Violation  of  the  Ordinance. 

The  Board  of  Trustees  of  the  City  of  San  Mateo  do  ordain  as  follows: 

Section  1.  All  pools  of  water,  or  other  places  in  which  mosquitoes  are  being 
bred,  are  hereby  declared  to  be  a  public  nuisance.  The  Board  of  Health  of  San 
Mateo  is  hereby  given  authority,  and  it  is  made  its  duty,  upon  the  complaint,  in 
writing,  of  any  resident  of  said  city,  to  condemn  as  nuisances,  any  such  pools  of  water 
or  other  places  in  which  mosquitoes  are  being  bred,  and  order  the  summary  abate- 
ment thereof. 

Sec.  2.  Upon  being  notified  by  such  Board  of  Health,  of  the  existence  of  such 
pools  of  water  or  other  places  in  which  mosquitoes  are  bred,  and  that  the  same  has 
been  declared  a  public  nuisance  by  said  Board  of  Health,  it  shall  be  the  duty  of  the 
person  or  persons  responsible  for  the  maintenance  thereof,  to  forthwith  abate  such 
nuisance,  and  all  persons  refusing  or  neglecting  to  forthwith  abate  such  nuisances 


32  UNIVERSITY   OP   CALIFORNIA  —  EXPERIMENT   STATION. 

as  directed  by  said  Board  of  Health,  shall  be  deemed  guilty  of  misdemeanor,  and 
upon  conviction  thereof  shall  be  fined  not  more  than  fifty  (50)  dollars,  or  to  be 
imprisoned  in  the  county  jail  not  more  than  twenty-five  (25)  days,  or  by  both 
sucli    fine    and    imprisonment. 

Sec.  3.     This  ordinance  shall  take  effect  and  be  in  force  from  and  after  fifteen 
days  after  its  passage. 

Introduced  the  24th  day  of  July,  1905. 

Passed   and   adopted   as   an   ordinance   of   the   city   of   San   Mateo,   this    17th   day 
of  July,  1905,  by  the  following  vote  : 

Ayes,  and  in  favor  of  the  passage  of  said  ordinance — Trustees  J.  H.  Hatch,  Geo.  A. 
Kertell,  M.  J.  Powers,  J.  P.  Weller,  W.  H.  Brown. 
Noes,  and  against  the  passage  of  said  ordinance — None. 
Absent — None. 

Wm.  H.  Brown, 
President  of  the  Board  of  Trustees  of  the  City  of  San  Mateo. 
[seal.]     Attest:  R.  H.  Jury, 

City  Clerk  and  ex-officio  Clerk  of  the  Board  of  Trustees 
of  the  City  of  San  Mateo. 


1 "   ...   '■". — r*"t ■> — .    ■     '  .  ■  , : — 7! " 

i^Ks&S-r      .    0     ■     • 

pP 

*>  -          *  V*J 

v,  ~;  ^      :** 

FIG.  24.    Scene  in  the  Burlingame  gardens  in  1904.     Workmen  were   obliged  to  wear 
netting  for  protection  against  mosquitoes.    Such  apparatus  was  not  seen  in  1905. 

RESULTS   OF   THE   CAMPAIGN. 

During  the  summer  of  1904  the  mosquitoes  in  the  Burlingame  district 
were  almost  intolerable.  Gardeners  and  other  workmen  were  obliged 
to  wear  mosquito  netting  for  protection.  In  walking  along  the  roads 
in  the  vicinity  of  the  hills  mosquitoes  would  gather  so  abundantly  on 
one's  clothes  that  sometimes  the  color  of  the  suit  was  almost  obscured 
beneath  the  general  effect  of  the  light  brown  produced  by  the  marsh 
mosquito.  It  has  been  stated  in  another  connection  that  on  one  occa- 
sion a  pint  measure  of  mosquitoes  was  captured  in  five  minutes'  sweep- 
ing !  These  were,  without  exception,  Ochlerotatus  lativittatus  from  the 
salt  marsh. 

Owing  to  the  delay  due  to  the  extensive  repairs  on  the  dike,  a  brood  of 
mosquitoes  emerged  from  the  diked  area  before  our  control  work  became 


MOSQUITO   CONTROL   WORK  IN   CALIFORNIA.  33 

effective.  They  consisted,  partly,  of  the  brown  marsh  species,  Ochlero- 
tatus  lativittatus,  but  mostly  of  the  gray  marsh  species,  L.  squamiger. 
These  made  their  way  to  the  hills  opposite  their  breeding  ground,  and 
squamiger  got  as  far  south  as  Burlingame  and  San  Mateo,  while  lativit- 
tatus was  limited  to  the  territory  about  Millbrae.  Squamiger  was  rather 
abundant  at  Burlingame  during  March  and  April,  but  gradually  dis- 
appeared until  late  in  June,  when  no  more  were  seen  during  the  season. 
An  occasional  incidens  was  sometimes  met  with,  due  to  the  fact  that 
a  few  fresh-water  pools  escaped  treatment;  but  their  numbers  were  so 
few  as  to  be  hardly  noticeable. 

Regarding  the  brown  marsh  species  (Ochlerotatus  lativittatus)  which 
were  so  abundant  and  vicious  in  preceding  years,  and  against  which  the 
main  work  of  the  campaign  was  directed,  the  rather  remarkable  result 
was  obtained  that  throughout  the  entire  season  in  the  Burlingame  section 
not  a  single  specimen  was  seen.  This  mosquito,  then,  was  practically 
annihilated  for  a  distance  of  10  miles  along  the  bay  shore,  and,  had  we 
been  able  to  get  on  the  diked  area  earlier,  squamiger  would  undoubtedly 
have  met  a  similar  fate.  As  it  was,  it  gave  practically  no  trouble  after 
May,  and  completely  disappeared  by  July.  It  may  be  argued  that  the 
season  or  some  other  condition  had  something  to  do  with  the  results. 
But  the  fact  that  they  were  abundant  enough  in  other  situations  about 
the  bay,  and  that  this  early  brood  gave  promise  of  a  good  season  for  the 
mosquito,  would  indicate  that  the  control  work  was  the  chief  factor  in 
the  problem,  in  view  of  the  fact  that  millions  of  larvae  were  killed  on  the 
marsh. 

The  ultimate  results  of  such  a  warfare  against  mosquitoes  can 
hardly  be  realized.  Before  the  campaign  was  well  started,  it  had  a 
direct  influence  upon  the  real  estate  of  the  district,  and  many  people 
were  induced  to  locate  in  the  territory  largely  on  the  basis  that  the 
mosquito  nuisance  was  solved.  This  region  is  essentially  a  country  of 
homes,  and  many  of  the  people  of  wealth,  having  their  business  interests 
in  San  Francisco,  come  here  to  live  during  the  summer.  They  come 
here  in  order  that  they  may  live  out  of  doors,  and  with  hordes  of 
hungry  mosquitoes  waiting  to  devour  them,  as  was  the  case  in  previous 
years,  the  desirability  of  inaugurating  a  warfare  against  the  pests  can 
at  once  be  appreciated. 

THE    SPECIES    CONCERNED. 

The  four  commonest  species,  and  the  only  ones  that  counted  very 
largely  in  the  control  work,  were :  Ochlerotatus  lativittatus,  Theobaldia 
incidens,  Culex  tarsalis,  and  Lepidoplatys  squamiger.  These  are  treated 
in  detail  in  the  following  pages,  while  there  is  added  synoptic  tables 
for  determining  the  adults,  and  a  bibliography  of  all  the  species  known 
to  occur  in  California. 
3— Bul  178 


34 


UNIVERSITY   OF   CALIFORNIA— EXPERIMENT   STATION. 


Ochlerotatus  lativittatus. 

Habits  of  the  Early  Stages.— The  eggs  of  this  species  are  laid,  so  far 
as  our  observations  go  during  the  past  year,  in  the  mud  of  pools  which 


4 


cf 


7 


<5~ 


70 


// 


•4>7n% 


FIG.  25.    Claws  of  Mosquitoes. 


1,    2, 


3 — First,  second  and  third  of  Culex  tarsalis. 
6— First,  second  and  third  of  Theobaldia  incidens. 
9— First,  second  and  third  of  Lepidoplatys  squamiger. 
10, 11,  12— First,  second  and  third  of  Ochlerotatus  lativittatus. 


4,    5, 

7, 


are  formed  by  the  monthly  high  tide,  and  which  dry  up  before  the  suc- 
ceeding high  tide  reaches  them.  This  was  demonstrated  several  times 
during  the  season  by  taking  mud  from  such  pools  and  submerging  it 


MOSQUITO   CONTROL  WORK   IN   CALIFORNIA. 


35 


with  ordinary  sea  water,  when  the  wrigglers  would  appear  in  from 
three  to  four  days.  Another  method  of  determining  this  egg-laying 
habit  consisted  in  sinking  ordinary  soap  boxes,  the  bottoms  first  being 
removed,  to  a  depth  of  two  or  three  inches  in  the  mud  of  pools  where 
larvae  were  likely  to  appear.  These  boxes  were  thoroughly  screened  on 
the  top  to  prevent  any  possible  entrance  of  adults,  and  were  kept  from 
floating  away  with  the  high  tides  by  means  of  stakes  driven  into  the 
ground.    When  the  high  tide  reaches  the  pool  the  mud  inclosed  by  the 


FIG.  26.    A  typical  breeding  pool  on  the  salt  marsh. 

higher  tides. 


Reached  only  by  the 


box  would  be  covered  with  water  through  seepage  from  below,  the  box 
being  high  enough  to  allow  no  water  to  enter  at  the  top,  thus  allowing 
no  possible  chance  for  the  eggs  to  be  deposited  in  the  water.  In  a  few 
days  larvae  would  appear  in  the  box  in  as  great  numbers  proportionally 
as  in  the  pool  outside  the  box.  This  egg-laying  habit  was  further  verified 
by  the  fact  that  throughout  the  season  there  were  no  instances  recorded 
where  larvae  appeared  in  permanent  pools,  or,  at  least,  where  there  was 
not  a  perceptible  lowering  of  the  water,  where  eggs  could  be  laid  at  the 
borders. 


36  UNIVERSITY   OF   CALIFORNIA  — EXPERIMENT   STATION. 

About  the  middle  of  May  of  the  present  year,  in  a  letter  addressed 
to  Professor  Smith,  of  New  Jersey,  we  stated  that  larvae  had  then  just 
begun  to  appear  in  the  large  tidal  creeks  on  the  reclaimed  land  opposite 
San  Mateo,  and  questioned  the  fact  that  in  this  case  the  eggs  were  laid 
in  the  mud.  Our  observations  since  that  time,  however,  tend  to  show 
that,  even  here,  the  eggs  were  laid  in  the  mud  of  the  creek  borders.  We 
were  led  to  doubt  the  habit  of  depositing  eggs  in  the  mud  here  because 
up  to  this  time  no  larvae  had  appeared,  and  there  was  no  perceptible 
lowering  of  the  creek,  while  in  the  smaller  pools  larvae  had  been  appear- 
ing for  a  couple  of  months. 

We  now  believe  that  this  lateness  of  the  larvae  was  due  to  the  tem- 
perature of  these  large  bodies  of  water  not  being  sufficiently  high  to 
favor  the  development  of  the  eggs.  These  creeks  were  also  seen  to  lower 
considerably  later  in  the  season,  which  would  afford  abundant  oppor- 
tunity for  egg  laying  at  the  borders  in  the  previous  season.  Moreover, 
larvae  in  the  smaller  pools  appeared  more  abundantly  each  month  until 
June,  despite  the  fact  that  no  adults  were  seen  in  the  vicinity  during 
the  present  season.  This  can  be  accounted  for  only  through  the  fact 
that  the  eggs  which  were  laid  during  the  previous  season  did  not  all 
hatch  with  the  high  tides  of  early  spring,  the  great  majority  not  appear- 
ing until  the  higher  temperature  of  May  and  June. 

The  larvae  of  this  species  are  not  confined  to  brackish  water  only, 
or  to  normal  sea  water,  but  may  develop  abundantly  in  water  of  a 
higher  saline  content  than  even  sea  water.  The  water  in  a  number  of 
instances  where  lativittatus  larvae  were  found  tested  4.5  per  cent  of 
salt,  or  1  per  cent  higher  than  normal  sea  water. 

An  experiment  to  test  the  effect  of  a  change  of  these  larvae  to  fresh 
water  was  made,  and  a  number  were  placed  in  pure  rain  water,  but 
they  seemed  to  enjoy  the  change  and  went  through  their  development 
in  due  course  of  time. 

The  typical  places  where  lativittatus  larvae  were  found  were  the  pools 
and  depressions  bordering  the  edge  of  the  marsh,  where  only  the  water 
of  the  monthly  high  tide  found  its  way.  After  the  rains  had  ceased  in 
the  spring  the  broods  appeared  as  regularly  as  the  tides  themselves,  as 
may  be  seen  from  the  table  on  the  opposite  page.  These  larvae  were 
first  seen  on  February  20th  in  1905,  and  the  last  brood  in  1904  disap- 
peared on  September  25th.  They  were  generally  found  in  pools  or 
situations  which  contained  rather  clean  water,  but  in  the  diked  area 
they  were  found  in  water  highly  impregnated  with  a  reddish  mineral 
deposit,  probably  ferric  iron.  This  gave  the  water  a  distinctly  reddish- 
brown  color,  and  the  larvae  and  pupae  taken  from  such  pools  were 
covered  over  with  a  coating  of  the  same  deposit. 


MOSQUITO   CONTROL  WORK   IN   CALIFORNIA. 


37 


Table  showing  Relation  of  Tides  to  Appearance  of  Broods  of  Ochlerolatus  lativittatus. 

The  heights,  in  feet  and  tenths,  are  from  the  soundings  of  the  Coast  and  Geodetic 
Survey  for  this  region.  The  appearance  of  broods  was  checked  up  from  our  notes.  The 
observations  were  made  on  practically  the  same  pools  extending  for  five  miles  along  th" 
marsh,  and  which  were  reached  only  by  the  monthly  high  tide,  and  which  dried  up  in 
from  ten  days  to  three  weeks. 


b 

SB 

MAY. 

JUNE. 

JULY. 

W 

> 

s 

> 

W 

► 

*& 

S3 

^2. 

gg 

4g 

S2 

J»CTQ 

o  § 

p'ap 

o  a 

»JQ 

o  s 

Moon. 

2P 

P   66 

Moon. 

ST  & 

0  p 

Moon. 

-i 

£  so 

' 

'""'■  »-* 

1       1 

1 

S3 

'       1 

tf  3 

1      1 

e+  ^ 

1 

:  w 

°  2 

i  a 

o  o 

w 

o  o 

<0  ^> 

Hi- 

03 

co 

CO 

, 

de. 

>       O 

Uq 

O 

Crq 

i    o 

' 

fr1 

'       ^*> 

S" 

& 

■        M> 

Feet. 

Feet. 

1 

?eet. 

1 

5.2 

5.5 

5.8 

2 

5.2 

New 

5.6 

New 

5.8 

3 

5.2 

5.6 

5.8 

4 

New . 

5.2 

5.6 

5 

5.2 

5.7 

6 

5.5 

5.4 

7 

5.3 

5.3 

5.2 

8 

5.3 

5.0 

5.4 

9 

5.2 

5.1 

1st  quarter. _ 

5.4 

10 

5.0 

1st  quarter.. 

5.3 

5.6 

11 

1st  quarter. . 

4.8 

5.5 

5.8 

12 

4.5 

5.7 

5.9 

13 

5.3 

6.0 

6  1 

14 

5.5 

6.1 

6.2 

Larvae 

15 

5.7 

6.2 

Larvae 

6.1 

Larvae 

16 

5.9 

Full i 

Larvae 

Full  

6.0 

Larvae 

17 

6.1 

6.1 

Larvae 

5.7 

Larvae 

18 

Full 

6.1 

Larvae 

5.8 

Larvae 

Larvae 

19 

6.1 

Larvae 

Larvae 

5.4 

Larvae 

20 

Larvae 

5.5 

Pupae 

4.9 

Pupae 

21 

5.9 

Larvae 

5.1 

Pupae 

4.9 

Pupae 

22 

5.4 

Larvae 

5.0 

Pupae 

5.0 

Pupae 

23 

5.2 

Larvae 

5.1 

Adults 

5.0 

Adults 

24 

4.9 

Larvae 

3d  quarter  ._ 

5.2 

3d  quarter  __ 

25 

3d  quarter.  . 

5.0 

Pupae 

5.2 

5.2 

26 

5.1 

Pupae 

5.3 

5.3 

27 

5.2 

Pupae 

5.4 

5.5 

28 

5.3 

Pupae 

5.5 

5.6 

29 

5.3 

Adults 

5.6 

5.8 

30 

5.4 

5.8 

5.9 

31 

5.5 

New . 

5.9 

In  the  newly  reclaimed  land  north  of  San  Mateo  there  are  some  areas 
which  contain  numerous  cracks  in  which  the  water  stands  at  a  couple 
of  feet  below  the  surface.  A  search  in  these  failed  to  find  any  larvae, 
and  we  were  informed  by  people  living  on  this  land  that  they  were 
seldom  troubled  with  mosquitoes.  That  they  were  not  found  in  such 
situations  may  be  due  to  the  high  mineral  content  of  the  water,  or 
that  they  are  not  favorable  places  for  egg  laying.  The  chemist  of  the 
salt  works  in  the  vicinity  stated  that  there  was  seldom  any  life  found 
in  these  deeper  cracks,  because  of  the  mineral  matter  contained  in  the 
water.  The  appearance  of  larvae  in  the  cracks  in  the  diked  area  was 
confined  to  the  early  part  of  the  season,  none  being  seen  after  April, 
and  these  may  have  come  in  as  the  water  became  lowered  from  the  sur- 
face level  where  it  stood  before  the  dike  was  put  in  repair. 


38 


UNIVERSITY   OP   CALIFORNIA  — EXPERIMENT   STATION. 


Habits  of  the  Adult. — This  mosquito,  hatching  from  its  breeding 
place  on  the  salt  marsh,  makes  its  way  inland,  usually  in  the  direction 
of  favorable  winds.  During  June,  1904,  they  were  found  abundantly 
in  the  hills  beyond  the  Spring  Valley  lakes,  a  distance  of  10  miles  from 
the  salt  marsh.     They  are  active  all  day,  but  particularly  late  in  the 


FIG.  27.    Genitalia. 

1.  Ochlerotatus  lativittatus.  3.    Culex  tarsalis. 

2.  Theobaldia  incidens.  4.     Lepidoplatys  squamiger. 

afternoon  and  early  evening,  when  there  is  but  little  wind.  They  have 
been  seen  to  congregate  in  innumerable  numbers  in  the  wooded  canons 
of  the  hill  slopes  in  the  Burlingame  section,  and  make  life  interesting 
for  man  as  well  as  stock.  This  species  is  particularly  bold  and  vicious, 
and  does  not  hesitate  to  thrust  its  beak  through  a  couple  of  thicknesses 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA. 


39 


of  clothing.  It  is  not  as  troublesome  in  houses  and  is  seldom  found 
there,  but  prefers  the  sheltered  places  out  of  doors.  It  can,  however, 
readily  make  its  way  through  ordinary  mosquito  netting,  as  was  observed 
in  our  breeding  cages,  which  were  first  covered  with  this  article.     And 


<*17)9( 


FIG.  28.     Ochlerotatus  lativittatus. 
1,  larva;  2,  antennse;  3,  mentum;  4,  spines  on  breathing  siphon,  showing 
variation;  5,  scale  of  eighth  abdominal  segment;  6,  eighth  and  ninth  abdom- 
inal segments  and  siphon  ;  all  enlarged. 


here  it  might  be  stated  that  there  should  be  a  demand  created  for  netting 
of  a  finer  mesh  than  that  now  in  common  use,  to  compel  the  manufac- 
turers to  supply  this  demand.  The  netting  or  screens  now  in  the 
market  allow  some  species  to  go  through  very  readily,  and  as  we  are 


40  UNIVERSITY   OF   CALIFORNIA— EXPERIMENT   STATION. 

writing  this,  in  spite  of  the  fact  that  the  windows  of  the  room  are  sup- 
posed to  be  well  screened,  we  have  captured  four  species  of  mosquitoes, 
two  of  which  are  Anopheles. 

The  males  of  this  species  were  found  nowhere  except  on  the  marsh 
or  in  very  close  proximity  to  their  breeding  ground.  The  females  that 
were  found  on  the  hills  during  the  present  year  were  not  found  to 
contain  eggs;  but  since  there  was  but  a  single  brood,  and  these  not 
very  abundant,  further  observations  are  necessary  before  it  is  safe  to 
form  a  conclusion  as  to  whether  or  not  the  migratory  forms  are  barren. 

Description  of  Larva.— Length  of  full-grown  larva  to  tip  of  breathing 
tubes,  7-8  mm.  Head  broadest  opposite  the  eyes.  There  is  a  tuft  of 
three  or  four  hairs  near  the  base  of  the  antennae  and  one  or  two  smaller 
ones  more  posteriorly.  A  rectangle  is  formed  by  four  single  hairs 
about  the  middle  of  the  vertex.  The  antenna  is  of  moderate  length,  of 
about  the  same  thickness  throughout,  slightly  curved  inward,  and  bear- 
ing short  scattered  spines  upon  its  surface.  At  its  middle  point  is  a 
small  tuft  of  four  or  five  hairs,  and  at  the  apex  is  one  long  and  three 


FIG.  29.    Wing  of  Ochlerotatus  lativittatus,    $. 

shorter  spines,  and  a  blunt,  peg-like  process.  The  mouth  brushes  are 
rather  large,  with  the  hairs  on  the  inner  side  curved  at  the  tip  and 
pectinated.  The  mentum  is  normally  triangular,  with  9  to  10  uniform 
teeth  on  each  side  of  the  apex.  On  the  eighth  abdominal  segment  are 
22  to  25  scales,  with  spines  at  the  tip  and  along  the  sides  pointing  in  the 
same  direction.  The  respiratory  siphon  is  about  two  and  one  half 
times  as  long  as  wide  at  base ;  the  lateral  rows  of  spines,  extending  about 
half-way  to  apex,  consist  of  18  to  20  spines,  rather  long  and  toothed  at 
the  sides.  The  ninth  segment  is  longer  than  broad,  with  two  or  three 
dorsal  and  a  row  of  12  to  15  ventral  tufts  at  apex.  The  tracheal  gills 
are  shorter  than  the  segment. 

Description  of  Adult.— A  very  light  brown  mosquito,  almost  straw 
color,  with  brown  stripes  on  thorax.  It  is  of  medium  size,  and  the 
hind  tarsal  joints  are  banded  at  both  base  and  apex,  the  last  one  being 
wholly  white. 

Head  black;  scales  light  yellow,  with  darker  erect  forked  ones  pos- 
teriorly; palpi  and  beak  dark  brown. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA.  41 

Thorax  with  golden-brown  scales,  a  strip  of  brown  ones  on  each 
side  of  median  line ;  femora  and  tibia  yellowish  brown,  darker  at 
apices.  Tarsi  light  brown,  the  front  one  having  base  and  apex  of  first 
two  joints  and  base  of  third  white ;  the  middle  one  with  base  and  apex 
of  first  three  and  base  of  fourth  white;  the  last  one  with  the  first  four 
joints  at  base  and  apex  and  the  fifth  wholly  white.  The  claws  are  all 
one-toothed. 

Wings  with  mixed  yellowish  white  and  brown  scales,  which  are  broad- 
ened at  tip.  Petiole  of  first  submarginal  cell  not  quite  as  long  as  that 
cell ;  cross  vein  at  apex  of  second  basal  cell  its  own  length  from  the  cross 
vein  above. 

Scales  on  abdomen  yellowish  white ;  two  large  rectangular  spots  of 
dark  brown  scales  on  each  side  of  median  line  of  segments  two  to  five 
the  appearance  of  two  broad  interrupted  bands. 

Genitalia. — Basal  clasp  segment  stout;  the  apical  segment  slender, 
with  a  slight  constriction  near  base,  widest  at  middle,  and  ending  in 
the  usual  spine.  Claspette  at  basal  third  of  clasp  segment;  a  row  of 
strong  spines  on  margin.  Basal  portion  of  harpes  setaceous,  with  three 
or  four  long  spines  on  inner  side  near  apex.  Terminal  segment  smooth, 
and  as  long  as  basal  part.  Harpago  stout,  bent,  ending  in  an  acute- 
recurved  hook.  Setaceous  lobes  prominent,  bearing  from  three  to  six 
stout  spines.     (See  Fig.  27.) 

Size,  6  mm.    Wing  expanse,  10-12  mm. 

Lepidoplatys  squamiger. 

Habits  of  Younger  Stages. — So  far  as  our  acquaintance  goes  with  this 
mosquito  during  the  past  season,  it  is  wholly  a  salt-marsh  form.  We 
were  on  the  lookout  for  this  species  in  fresh-water  pools  during  the 
season,  because  Professor  Smith  found  what  had  been  determined  as 
squamiger  in  New  Jersey  to  be  limited  entirely  to  fresh  water.  After 
Professor  Smith's  attention  was  called  to  this  difference  in  habits  he 
wrote  us  that  upon  closer  examination  it  proved  to  differ  from  the 
typical  California  squamiger,  and  that  it  was  a  new  species.  It  is  said 
that  this  squamiger  was  taken  at  San  Rafael  in  1904  in  one  or  two  cases 
in  fresh-water  pools.  It  is  not  improbable,  of  course,  that  this  species 
may  be  found  in  fresh  water,  but  if  one  season's  experience  will  justify 
the  conclusion  it  is  the  exception  to  find  it  in  such  situations  in  this 
particular  region. 

The  larvse  of  this  species  were  almost  invariably  found  in  the  identical 
situations  with  lativittatus,  which  has  already  been  fully  discussed. 
The  striking  difference  in  habits  of  the  two,  however,  is  in  the  fact  that 
lativittatus  is  many-brooded,  while  squamiger  is  limited  to  probably 
two.     Squamiger  larvae  were  about  as  common  as  Ochlerotatus  lativ- 


42 


UNIVERSITY   OF   CALIFORNIA — EXPERIMENT   STATION. 


ittatus  in  the  early  season,  but  they  were  not  seen  after  April.  They 
first  appeared  with  0.  lativittatus  February  20th,  but  disappeared  by 
the  last  week  in  April. 

Having  left  the  State  about  September  1st  we  were  unable  to  follow 
it  later  than  that  date,  but  the  control  work  of  the  present  season  would, 
in  all  probability,  have  prevented  any  further  broods  from  appearing 
anyway.  However,  in  a  trip  made  to  the  territory  on  September  20, 
1904,  adult  sqaamiger  were  flying  about  rather  abundantly,  and  males 


FIG.  30.    A  cattle-guard  on  the  Southern  Pacific  railroad.    A  case  where  man  helps 

the  mosquitoes. 

were  found  on  the  marsh,  which  would  indicate  that  a  brood  had  recently 
emerged. 

Negative  evidence  points  to  the  fact  that,  like  0.  lativittatus,  the  eggs 
remain  over  winter  and  hatch  in  the  following  February  or  March. 
Owing  to  the  early  disappearance  of  the  species  we  were  given  no 
opportunity  for  studying  the  egg-laying  habits;  but  since  the  larvae 
were  found  in  the  same  situations  with  0.  lativittatus,  it  is  likely  that 
the  egg-laying  habit  is  similar  in  the  two  species. 


Habits  of  Adult. — This  species  is  also  migratory,  and  while  it  was 
not  found  across  the  hills  toward  the  ocean,  as  was  0.  lativittatus,  it  was 


MOSQUITO   CONTROL  WORK  IN   CALIFORNIA. 


43 


found  abundantly  enough  at  Burlingame  and  San  Mateo,  and  in  the 
hills  at  least  three  or  four  miles  from  its  breeding  ground. 

This  was  the  only  species  that  appeared  in  numbers  during  the  past 
season   in  Burlingame,   and  this  was  due   to   an   early  brood  which 


e^9f 


FIG.  31.    Lepidoplatys  sqxtamiger. 

1,  larva;  2,  antennae;  3,  mentum;  4,  siphonal  spines,  showing  variation; 
5,  scale  of  eighth  abdominal  segment;  6,  eighth  and  ninth  abdominal  seg- 
ments and  siphon;  all  enlarged. 

emerged  from  the  diked  area.  No  adults  emerged,  to  our  knowledge, 
after  March  25th,  but  a  few  still  persisted  in  the  residence  section 
until  July  1st,  which  would  seem  to  indicate  that  the  maximum  adult 
life  may  be  three  months.    In  our  notes  it  is  recorded  that  on  May  16th 


44  UNIVERSITY   OF   CALIFORNIA— EXPERIMENT   STATION. 

adults  of  squamiger  were  common  on  the  marsh,  and  all  were  females 
with  eggs  well  developed.  The  egg-laying,  therefore,  may  be  pro- 
longed for  nearly  two  months  after  emergence;  altogether,  our  notes 
on  this  species  indicate  that  it  is  longer  lived  than  the  others  of  this 
section.  Its  biting  propensities  are  about  as  well  developed  as  the 
brown  marsh  species,  and  the  only  thing  that  prevents  it  occupying  a 
place  of  annoyance  equal  to  0.  lativittatus  is  that  it  is  fewer-brooded, 
and  consequently  less  in  numbers. 

In  1905  the  first  adults  of  this  species  were  seen  on  February  27th 
and  the  last  on  July  2d.  In  1904  a  brood  was  observed  in  the  middle 
of  September.  Three  or  four  specimens  taken  in  the  hills,  in  April, 
about  three  miles  from  the  marsh,  had  eggs  partly  developed,  but  these 
were  the  only  ones  seen  with  eggs,  excepting  on  the  marsh.  The  great 
majority  of  those  that  made  their  way  to  the  hills  never  returned  to 
the  marsh.  No  adults  were  seen  on  the  marsh  after  the  middle  of  May, 
although  they  were  seen  in  the  hills  up  to  July  1st. 

Description  of  Larva.— Length  of  full-grown  larva  to  tip  of  breath- 
ing tubes,  10  mm.  A  robust  larva  usually  of  a  dark  gray  color.  Head 
broader  than  long,  widest  just  posterior  to  the  eyes.  Near  the  base 
of  the  antennas  is  a  tuft  of  four  or  five  hairs.  The  antennae  are  short, 
slightly  curved  inward,  with  a  small  tuft  of  hairs  at  the  middle  not 
reaching  to  apex,  and  with  scattered  spines  over  its  surface.  The  apex 
is  terminated  in  one  long  spine,  often  crooked,  one  about  one  half  as 
long,  and  two  shorter  ones,  and  with  a  small,  peg-like  process.  The 
mouth  brushes  are  composed  of  a  thick  mat  of  hairs  curving  inward, 
those  on  the  inner  side  being  sharply  curved  at  tip  and  finely  pectinated. 
The  mentum  is  broadly  triangular,  with  9  to  10  uniform  teeth  on  each 
side  of  apex.  The  lateral  patches  of  scales  on  the  eighth  segment  are 
composed  of  from  26  to  30  scales,  each  scale  being  armed  at  the  tip  with 
spines,  those  at  the  tip  being  the  longest.  Respiratory  siphon  not  more 
than  three  times  as  long  as  broad  at  base,  two  rows  of  toothed  spines 
extending  from  base  to  about  middle;  near  the  end  of  row  is  a  small 
tuft  of  four  or  five  hairs.  Ninth  segment  longer  than  broad,  bearing 
two  dorsal  tufts  and  a  ventral  row  of  twelve  or  fifteen  tufts.  Tracheal 
gills  short,  not  exceeding  width  of  segment. 

Description  of  Adult.— A  rather  large  mosquito,  with  very  sealy 
wings.  Scales  mixed  with  white  and  black,  giving  a  general  color  of 
gray.     Base  of  tarsal  joints  and  segments  of  abdomen  white. 

Head  black,  with  whitish  scales  on  posterior  part;  palpi  with  beak 
lighter  brown  in  middle,  with  apical  fourth  darker;  antennae  dark 
brown. 

Scales  of  thorax  pale  yellow,  mixed  with  black  along  the  sides  and 
with  a  dark-brown  median  band  dorsally;  there  are  also  golden-brown 


MOSQUITO   CONTROL  WORK  IN   CALIFORNIA.  45 

scales  sparsely  scattered  over  thorax.  The  femora  are  pale  brown, 
lighter  beneath,  and  covered  with  white  and  black  scales,  more  numer- 
ous above.  The  tibia  are  darker  in  color,  with  mixed  white  and  black 
scales,  and  on  either  side  below  are  rather  long  black  hairs,  also  present 
on  femora  and  tarsi.  The  tarsi  are  black,  with  occasional  white  scales ; 
the  bases  are  banded  with  white  or  pale  yellow  scales,  more  prominent 
on  hind  tarsi ;  claws  single-toothed. 

The  wings  are  densely  clothed  with  white  and  dark-brown  scales, 
giving  a  general  color  of  gray.  The  scales  on  the  dorsal  two  thirds 
mostly  broad  and  truncate,  while  on  the  apical  third  long,  narrow  ones, 
tapering  slightly  at  each  end,  are  more  numerous.  Petiole  of  sub- 
marginal  cell  about  two  thirds  as  long  as  is  cell;  cross  vein  at  apex  of 
second  basal  at  least  equal  to  its  length  from  the  one  above  it. 

The  abdomen  is  black,  with  scattered  whitish  scales;  the  base  of  the 
segments  with  rather  broad  band  of  similarly  colored  scales. 

Genitalia. — Basal  segment  strongly  curved  on  inner  side,  broadening 
just  before  tip.  Apical  segment  rather  strongly  curved  at  tip,  ending 
in  an  articulate  spine.  Claspette  setaceous,  and  situated  at  base  of 
basal  segment.  Harpes  long,  jointed,  ending  in  blunt  process,  which 
surrounds  base  of  apical  joint;  inner  side  strongly  setaceous.  Apical 
joint  abruptly  bent  at  basal  one  third  and  curved  at  tip.  Harpago  not 
quite  reaching  to  apex  of  basal  joint  of  harpe.  Tip  heavily  chitinizell 
and  recurved.  Setaceous  lobes  acutely  pointed,  bearing  two  or  three 
long  spines  at  tip.     (See  Fig.  27.) 

Size,  7  mm.    Wing  expanse,  12-15  mm. 

Theobaldia  incidens. 

Habits  of  Early  Stages.— This  is  the  commonest  fresh-water  mos- 
quito in  the  bay  region,  and  may  be  found  in  every  conceivable  place 
where  there  is  standing  water.  The  small  pools  and  containers  of  water 
about  residences  are  sure  to  be  stocked  with  this  mosquito.  It  may 
breed  in  very  foul  water,  and  has  been  found  at  the  outlet  of  sewers. 
It  is  also  the  commonest  species  breeding  in  the  creeks  in  this  section. 
The  eggs  occur  in  raft-like  masses  of  a  hundred  or  more.  They 
are  very  conspicuous  floating  upon  the  surface  of  the  water.  Larva? 
of  this  species  have  been  found  from  January  to  November. 

Habits  of  Adult. — This  is  the  typical  house  mosquito  of  the  section, 
and  will  find  its  way  into  houses  if  there  is  any  opportunity  for  entering. 
Next  to  the  salt-marsh  species  it  is  the  most  troublesome,  and  is  a  ready 
biter.  Specimens  may  be  found  at  any  season  of  the  year,  though 
they  are  not  active  for  two  or  three  months  during  the  winter.    At  this 


46 


UNIVERSITY   OF   CALIFORNIA — EXPERIMENT   STATION. 


season  they  have  been  found  in  cellars,  under  stone  bridges  and  other 
protected  places,  and  seemed  to  be  partly  hibernating.  The  species 
may  be  met  with  at  any  time  of  day,  but  are  more  in  evidence  toward 
evening.  So  far  as  is  known  it  goes  but  a  few  hundred  yards  from  its 


<?}?0f 


FIG.  32.     Theobaldia  incidens. 


1,  larva;  2,  antennae;  3,  mentum ;  4,  siphonal  spines,  showing  variation; 
5,  scale  of  eighth  abdominal  segment;  6,  eighth  and  ninth  abdominal  seg- 
ments and  siphon;  all  enlarged. 

breeding  place,  and  if  it  is  troublesome  in  the  house  its  breeding  ground 
will  more  than  likely  be  found  on  the  premises. 

Description  of  Larva. — Length  of  adult  larva  to  tip  of  breathing 
tube,  10-11  mm.    A  robust  larva  of  dark  gray  or  greenish  color.    Head 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA.  47 

broadest  posteriorly ;  on  vertex,  forming  a  slight  arch  with  the  antennae, 
are  six  tufts  of  hairs,  three  on  each  side  of  median  line,  the  two  central 
ones  being  farthest  apart.  The  antennae  are  short,  curved  inward, 
slightly  tapering  toward  tip,  with  a  tuft  of  hairs  on  upper  side  slightly 
proximal  to  middle,  and  bearing  at  its  tip  four  spines,  two  at  the  ex- 
treme tip  and  two  just  back  of  tip,  and  an  articulated  truncate  peg. 
The  mouth  brushes  with  hairs  on  inner  side  slightly  curved  at  tip  and 
finely  pectinated.  The  mentum  triangular,  with  12  to  14  teeth,  slightly 
larger  toward  base,  on  each  side  of  apical  tooth,  which  is  largest. 
Scales  on  eighth  abdominal  segment  arranged  in  triangular  form  and 
numbering  50  to  55.  Each  scale  bears  rather  long  spines,  which  are 
not  spreading.  Respiratory  siphon  three  times  as  long  as  width  at 
base ;  on  each  side,  extending  about  two  thirds  of  the  way  to  apex,  are 
two  rows  of  spines,  those  at  the  proximal  one  third  toothed,  while  the 
rest  are  long,  slender,  and  hair-like.  The  ninth  segment  is  slightly  longer 
than  broad,  with  three  or  four  tufts  on  dorsal  side,  and  a  row  of  12  to 
15  on  ventral  side.  The  tracheal  gills  are  about  one  and  one  fourth 
times  the  length  of  segment. 

Description  of  Adult. — A  large  mosquito,  with  prominent  black  spots 
on  the  wings.  The  only  other  California  species,  excepting  Anopheles, 
with  spotted  wings  is  annulatus,  which  may  be  distinguished  by  the 
bands  on  middle  of  tarsal  joints.  Head  black,  with  golden-brown  scales 
on  occiput,  erect  forked  ones  on  posterior  margin;  in  front  are  long, 
curved,  black  bristles,  projecting  forward.  The  eyes  are  immediately 
surrounded  with  a  narrow  stripe  of  straw  color;  palpi  annulate  with 
dark  brown,  becoming  darker  at  tip.     Antennae  dark  brown. 

Thorax  with  black  and  golden-brown  scales,  and  numerous  black 
bristles,  those  over  base  of  wing  brown.  Two  narrow  prominent  stripes 
of  black  scales  extending  one  each  side  of  median  line  from  anterior 
edge  to  base  of  wings. 

Wings  clothed  throughout  with  narrow  linear  scales.  A  cluster 
of  such  scales  occurs  on  radius  2  just  anterior  to  cross  vein  connecting 
with  radius  4,  one  at  point  of  branching  of  radius  1  and  2,  and  a 
third  at  the  junction  of  medial  1  and  2.  Petiole  of  first  submarginal 
cell  about  one  half  the  length  of  that  cell ;  cross  vein  at  apex  of  second 
basal  cell  meeting,  or  very  nearly,  with  the  one  above  it. 

Femora  dark  brown  to  black  above  with  scattered  white  scales,  below 
and  at  extreme  tip  white ;  tibia  black  above,  whitish  below,  and  narrowly 
banded  at  tip  with  white;  tarsi  of  almost  uniformly  dark  brown,  with 
very  faint  markings  of  yellow  at  apices.     Claws  simple. 

Genitalia. — Basal  segment  of  clasp  short  and  stout,  suddenly  nar- 
rowed on  inner  side  near  apex.  Terminal  clasp  segment  tapering  grad- 
ually to  tip.     Claspette  a  prominent  pyramidal  lobe,  bearing  two  stout 


48  UNIVERSITY   OF   CALIFORNIA— EXPERIMENT   STATION. 

spines  at  apex.     *Harpagones  rather  broad,  straight,  central  processes, 
ending  in  a  curved  hook.     Setaceous  lobes  obtusely  rounded,  with  7 
to  9  slender  spines.    Between  these  is  a  median  lobe,  bearing  eight  very 
stout  and  bluntly  pointed  spines.     (See  Fig.  27.) 
Size,  7  mm.  Wing  expanse,  15  mm. 

Culex  tarsalis. 

Habits  of  Younger  Stages.— The  larvas  of  this  species  were  found  in 
the  same  situations  as  incidens.  It  is  not  so  widespread,  however,  and 
incidens  may  be  found  without  tarsalis,  but  the  converse  of  this  was 
seldom  observed.  It  was  never  found  in  foul  water,  and  seems  to  prefer 
the  clearer  pools.  No  pool  was  seen  swarming  with  these  larvas,  and 
they  appear  not  to  be  as  rapid  breeders  as  incidens. 

Habits  of  the  Adult. — Little  opportunity  was  afforded  for  studying 
the  habits  of  the  adult  of  this  species,  since  they  were  but  rarely  met 
with.  Those  that  were  seen  occurred  with  incidens,  and  it  is  probable 
that  the  habits  of  the  two  are  somewhat  similar. 

Description  of  Larva. — Length  of  adult  larva  to  tip  of  breathing 
tube,  8-9  mm.  Head  broadest  at  eyes,  abruptly  narrowed  before  the 
antennas ;  on  vertex  just  above  the  antennas  is  a  tuft  of  6  to  7  hairs,  two 
similar  tufts  on  each  side  of  median  line  on  the  middle  of  vertex,  and 
a  small  tuft  of  three  or  four  hairs  above  and  below  the  eyes.  The 
antennas  are  long,  slightly  curved  inward,  of  about  the  same  thickness 
to  the  tuft,  where  it  suddenly  narrows,  the  whole  surface  being  covered 
with  scattering  hairs;  the  tuft  is  on  the  apical  one  third  and  consists 
of  20  to  30  hairs.  At  the  tip  are  three  long  spines  and  one  short  one, 
and  a  short,  stout  peg;  the  antennas  are  narrowed  slightly  at  the  base, 
and  arise  from  a  shoulder  of  the  head. 

The  mouth  brushes  are  long  and  wide  apart,  with  long  scattered 
straight  hairs  on  the  inner  side.  The  mentum  is  rather  sharp  pointed 
and  with  9  to  10  teeth  on  a  side,  the  apical  one,  and  the  ^cond  and 
third,  being  the  largest.  The  scales  on  the  eighth  segment  number  32 
to  35,  with  walled  spines  at  the  tip  and  sides.  The  respiratory  siphon 
is  at  least  four  times  as  long  as  broad  at  base.  The  rows  of  spines, 
consisting  of  12  to  15,  extend  about  one  third  way  to  apex;  the  spines 
are  broad,  short  and  many-toothed ;  there  are  three  or  four  tufts  at 
middle  and  one  near  the  apex.  The  ninth  segment  about  as  long  as 
broad,  with  the  usual  apical  tufts  of  hairs.  The  tracheal  gills  are  about 
one  and  one  fourth  times  the  length  of  segment. 

*  Dr.  Felt,  N.  Y.  State  Museum  Bulletin  97,  p.  480,  records  these  as  wanting, 
while  Dr.  Dyer,  N.  Y.  Jour.  Ent.  Soc,  Vol.  XIII,  p.  55,  describes  them  as 
"cylindrical  and  truncate."  If  we  have  homologized  the  parts  correctly  they  are 
distinctly  visible,  particularly  in  potash  preparation. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA. 


49 


Description  of  Adult.— A  medium-sized  mosquito  with  brown  thorax, 
and  black  abdomen  with  white  bands.  Beak  banded,  and  tarsal  joints 
white  at  both  base  and  apex. 


s  M 


Cmvf 


FIG.  33.     Culex  tarsalis. 

1,  larva;  2,  antennae;  3,  mentum;  ■!,  siphonal  spines,  showing  variation; 
5,  scale  of  eighth  abdominal  segment;  6,  eighth  and  ninth  abdominal  seg- 
ments and  siphon;  all  enlarged. 

Head  with  yellowish-brown  tomentum  on  occiput  and  furcate  at  tip ; 
palpi  uniformly  black ;  beak  black,  with  broad  band  of  white  at  middle. 

Thorax  brown  to  black,  with  golden-brown  tomentum  on  dorsum ; 
plurae  whitish ;  femora  black  above,  and  below  and  at  tips  white ;  tibia 
4-Bul  178 


50 


UNIVERSITY   OF   CALIFORNIA— EXPERIMENT   STATION. 


black,  with  base  and  apex  white ;  tarsi  black,  and  banded  with  white 
at  both  ends.    Claws  all  simple,  bearing  no  teeth. 

Wings  with  dark-brown  slender  scales  throughout.  Petiole  of  first 
submarginal  cell  about  one  half  the  length  of  that  cell;  cross  vein  at 
end  of  second  basal  less  than  its  length  from  the  one  above  it. 

Abdomen  black,  with  well-defined  bands  at  base  of  segments;  venter 
white. 

Genitalia. — Basal  segment  of  clasp  curved,  suddenly  narrowed  on 
inner  side  near  tip.  Apical  segment  stout,  tapering  to  tip ;  terminal 
spine  present.  Claspette,  situated  on  apical  one  third  of  basal  segment, 
is  composed  of  a  conspicuous  spatulate  organ,  two  curved  spines,  and 


FIG.  34.    Wings  of  Culex  tarsalis;     9   above;     $   below. 

three  closely  set  stout  spines,  which  are  generally  recurved  at  the  tip. 
Harpes  stout,  bearing  at  apex  a  tuft  of  stout  spines.  Harpago  bearing 
at  its  tip  conspicuous  stout  teeth  arising  in  different  planes.  Setaceous 
lobes  broadly  rounded  and  bearing  slender  spines.     (See  Fig.  27.) 


Other  Species. 

Besides  the  four  troublesome  species  already  described  in  detail 
there  were  found  early  in  the  season  in  a  cattle-guard  on  the  Southern 
Pacific  Railroad  at  Millbrae  the  larva?  of  variapalpus,  and  a  few  adults 
were  also  taken  in  the  vicinity.  Nothing  was  seen  of  this  species  after 
the  middle  of  April,  though,  of  course,  the  control  work  may  have  had 
something  to  do  with  this. 


MOSQUITO   CONTROL   WORK   IN    CALIFORNIA. 


51 


Anopheles  maculipennis  was  taken  from  the  pond  along  the  earline 
one  half  mile  north  of  the  Burlingame  depot,  and  also  from  another 
pond  on  the  west  side  of  the  county  road  opposite  the  Blackhawk  dairy. 
The  larvae  were  fairly  common  here,  and  males  were  collected  from  the 


\\    2. 


m^^^mi&mmBWMflM\ 


WtoBrnmnrm 


^^^'^^ 


"XT  4 


FIG.  35. 

1.  Theobaldia  inczdens    9  3.  Lepidoplatys  squamiger   9 

2.  Culex  tarsalis  9  4.  Ochlerotatus   lativittatus    9 

grass  by  sweeping.  A  trip  was  made  to  San  Rafael  on  June  8th,  and 
the  marshes  to  the  east  of  the  town  were  visited.  Here,  in  the  wide  tidal 
creeks  in  land  that  was  partly  reclaimed,  we  expected  to  find  0.  lativ- 
ittatus larvae,  but  were  surprised  to  find  Anopheles  maculipennis  the 
commonest  form,  although  the  water  was  distinctly  brackish. 


52  UNIVERSITY   OF   CALIFORNI A  —  EXPERIMENT   STATION. 


SYNOPTIC    TABLES. 

The  following  synoptic  tables  include  all  the  species  known  to  occur 
in  California  at  the  present  writing : 

Table  for  determining  the  Genera  and  Species  of  California  Culicidse. 

a.  Legs  densely  clothed  with  coarse  erect  scales Psopophora  ciliata. 

a.  Legs  not  densely  clothed  with  coarse  erect  scales. 

b.  Palpi,  in  females,  as  long  as  beak Anopheles. 

c.  Palpi  of  uniform  color. 

(1.  Wings  with  conspicuous  rectangular  yellowish-white 

spots  on  apical  fourth  of  front  margin A.  punctipennis. 

dd.  Wings  without  such  spots A.  maculipennis. 

cc.  Palpi  banded ;   light  area   at  base  of  three   distal  seg- 
ments   A.  franciscanus. 

bb.  Palpi  in  female  not  as  long  as  beak. 
c.  Tarsal  claws  toothed. 

d.  Lateral  wing  scales  narrow,  but  slightly  tapering  to 

bases Ochlerotatus. 

e.  Apices  of  palpi  and  ring  at  middle  white 0.  varipalpus. 

ee.  Palpi  not  so  marked. 

/.  Last  joint  of  hind  tarsi  wholly  white  . O.  lativittatus. 

ff.  Last  joint  of  hind  tarsi  not  wholly  white  ..0.  sylvestris. 
dd.  Lateral   wing    scales    generally   broad,   tapering   to 

bases Lepidoplatys  squamiger. 

cc.  Tarsal  claws  not  toothed. 

d.  Cross  vein  at  end  of  second  basal  cell  more  than  its 

length  from  the  one  above  it Culex. 

e.  Beak  banded C.  tarsalis. 

ee.  Beak  not  banded. 

/.  Segments  of  abdomen  banded  at  apex C.  territans. 

ff.  Segments  of  abdomen  banded  at  base C.  pipiens. 

dd.  Cross  vein  at  end  of  second  basal  cell  less  than  its 
length  from  the  one  above  it. 

e.  Wings  spotted Theobaldia. 

f.  Tarsal  joints  banded  at  middle T.  annulatus. 

ff.  Tarsal  joints  not  banded  at  middle T.  incidens. 

ee.  Wings  not  spotted Culiseta  consobrina. 


MOSQUITO   CONTROL   WORK   IN   CALIFORNIA.  53 

CULICIDAE  IN  CALIFORNIA.* 

1.  Anopheles   maculipennis  Meig.    (quadrimaculatus   Say,   annulimanus   Wulp). 

Aldrich,  J.  M.     Cat.  Diptera,  p.  121. 

Berkeley,  W.  N.     Laboratory  Work  with  Mosquitoes.     1902. 

Dyar,  H.  G.     Ent.  Soc.  Wash.  Proc,  5  :45-51.     1902. 

Ent.  Soc.  Wash.  Proc,  0:37-41.     1904. 

N.  Y.  Ent.  Soc.  Jour.,  11 :23-27.     1903. 

N.  Y.  Ent.  Soc.  Jour.,  13  :23.     1905. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  79.     (See  Index.) 

N.  Y.  St.  Mus.  Bull.  97.      (See  Index.) 

Giles,  G.  M.     Gnats  or  Mosquitoes,  p.  326.     1900. 

Howard,  L.  O.     U.  S.  Dept.  Agr.,  Bur.  Ent,  Bull.  25,  n.  s.,  1900. 

Mosquitoes.      3900. 

Johannsen,  O.  S.  N.  Y.  St.  Mus.  Bull.  68.  1903. 
Ludlow,  C.  S.  Medical  Record,  January  20,  1906. 
Smith,  J.  B.     N.  J.  Agr.  Ex.  Sta.  Bull.  171. 

■  N.  J.  Report  on  Mosquitoes,  p.  168.     1904. 

Theobald,  F.  V.     Monograph. 

2.  Anopheles  punctipennis  Say   (hiemalis  Fitch). 

Aldrich,  J.  M.    Cat.  Diptera,  p.  122. 

Dyar,  H.  G.     N.  Y.  Ent.   Soc.  Jour.,  10:194-201.     1902. 

N.  Y.  Ent.  Soc.  Jour.,  13  :23.     1905. 

Ent.  Soc.  Wash.  Proc,  5  :140-48.     1903. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  79.      (See  Index.) 

N.  Y.  St.  Mus.  Bull.  97.      (See  Index.) 

Fitch,  Asa.  Am.  Jour.  Agr.  Sci.,  5  :281-282.  1847. 
Giles,  G.  M.  Gnats  or  Mosquitoes,  p.  322.  1900. 
Howard,  L.  O.     U.  S.  Dept  Agr.,  Bur.  Ent.,  Bull.  25,  n.  s.,  1900. 

Mosquitoes,  1901. 

Johannsen,  O.  S.     N.  Y.  St  Mus.  Bull.  68.     1903. 
Lawrence.     Long  Island  Board  of  Health  Rept     1903. 
Ludlow,   C.    S.     Medical   Record,  January  20,   1906. 
Robinson,  F.  W.     Rept.  Eliz.  N.  J.,  pp.  1-15. 
Smith,  J.  B.     Rept.  N.  J.  Agr.  Ex.  Sta.  Bull.  171. 

Report  on  Mosquitoes,  p.  163.     1905. 

Theobald,   F.   V.     Monograph   of  Culicidjp. 

*  This  list  of  California  Culicidae  has  been  checked  up  through  the  courtesy  of 
Dr.  L.  O.  Howard,  by  Mr.  D.  W.  Coquillett,  of  the  Bureau  of  Entomology. 
Washington.  Mr.  C.  S.  Ludlow,  in  the  Medical  Record  for  January  20,  1906, 
also  records  dorsalis,  signifer,  and  spencerii  as  occurring  in  the  State. 

The  classification  of  Culicidae  has  recently  undergone  considerable  change,  par- 
ticularly within  the  old  genus  Culex,  which  is  in  the  above  list  represented  by  five 
genera.  Most  workers  in  the  group  are  agreed  on  the  genus  Culex  as  now  restricted, 
and  also  on  the  genera  Theobaldia  and  Culiseta.  There  is,  however,  not  a  general 
concurrence  on  the  other  two  genera,  and  to  aid  in  the  reference  to  the  literature 
which  has  appeared  during  the  last  year  or  two,  the  following  synonymy,  so  far 
as  it  concerns  the  California  species,  is  here  given  : 

Lepidoplatys  Coq.  =  Taeniorhynchus  Nev.  Lem.    (Coquillett), 

Grabhamia   Theob.     (Dyar), 
Culicada  Felt    (Felt). 
Ochlerotatus  Arrib.  =  Cylicada  Felt    (Felt), 

Ecculex    Felt    (Felt    and    Dyar), 
Taeniorhynchus   Nev.   Lem.    (Coquillett), 
Grabhamia  Theob.    (Dyar). 
The  species  curriei  has  been  redescribed  by  Mr.  Coquillett  as  lativittatus. 
Professor  Smith  has  since  stated  that  his  species  is  distinct  from  squamiger  and 
that  it  is  a  new  species, 


54  UNIVERSITY   OP   CALIFORNIA — EXPERIMENT   STATION. 

3.  Anopheles  franciscanus  McC. 

McCracken,  Isabel.     Ent.  News,  Jan.  1904. 
Dyar,  H.  G.    N.  Y.  Jour.  Ent.  Sec.,  13  :23.    1905. 
Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  97.     1905. 
Ludlow,  C.  S.    Medical  Record,  January  20,  1906. 

4.  Culex  tarsal  is  Coq.      (willistoni  Giles,  kelloggi  Theob.,  af  finis  Adams). 

Aldrich,  J.  M.     Cat.  Diptera,  p.  132. 
Coquillett,  D.  W.     Can.  Ent.,  28:43-44.     1896. 
Dyar,  H.  G.     Ent.  Soc.  Wash.  Proc,  6:37-41.     1904. 

Jour.  N.   Y.  Ent.  Soc,  13  :23.     1905. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  97.     1905. 

Howard,  L.  O.    U.  S.  Dept.  Agr.,  Bur.  Ent,  Bull.  25,  n.  s.,  1900. 

Mosquitoes.     1901. 

Ludlow,  C.  S.     Medical  Record,  January  20,  1906. 

5.  Culex  territans  Walk,    (apicalis  Adams). 

Aldrich,  J.  M.     Cat.  Diptera,  p.  132. 

Dyar,  H.  G.     Ent.  Soc.  Wash.  Proc,  5:140-48.     1903. 

■  Ent.  Soc.  Wash.  Proc,  6:37-41.     1904. 

■  Jour.  N.  Y.  Ent.  Soc,  13  :26.     1905. 

Felt,   E.  P.     N.  Y.   St.  Mus.  Bull.  79.     1904. 

N.  Y.  St.  Mus.  Bull.  97.     1905. 

Ludlow,  C.  S.     Medical  Record,  January  20,  1906. 
Smith,  J.  B.     Rept.  N.  J.  Agr.  Ex.  Sta.,  p.  325.     1905. 

6.  Culex  pipiens  L.   (aestuans  Wied.,  pungens  Wied.,  fatigans  Wied.,  boscii  Desv., 

cubensis,  Bigot). 

Aldrich,  J.  M.     Cat.  Diptera,  p.  130. 

Dyar,  H.  G.     N.  Y.  Ent.  Soc.  Jour.,  5:45-51.     1902. 

N.  Y.  Ent.   Soc.  Jour.,   10 :194-201.     1902. 

N.  Y.  Ent.  Soc.  Jour.,  13:26.     1905. 

Ent.  Soc.  Wash.  Proc,  5  :  140-48.     1903. 

Ent.  Soc.  Wash.  Proc,  6:40.     1904. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  79.     (See  Index.) 

N.  Y.  St.  Mus.  Bull.  97.     (See  Index.) 

Howard,  L.  O.    U.  S.  Dept.  Agr.,  Bur.  Ent.,  Bull.  25,  n.  s.,  1900. 

Mosquitoes,   1901. 

Johannsen,  O.  S.     N.  Y.   St.  Mus.  Bull.  68.     1903. 
Lawrence.     Long  Island  Board  of  Health  Rept. 
Ludlow,  C.  S.     Medical  Record,  January  20,  1906. 
Robinson,  W.  F.     Eliz.  N.  J.     Rept. 
Smith,  J.  B.     Ent.  News.  15:49-51. 

Rept.  N.  J.  Agr.  Ex.  Sta.,  p.  305.     1905. 

Van  Dine,  D.  L.     Agr.  Ex.   Sta.  Haw.,  Bull.  6. 

7.  Ochlerotatus  varipalpus   Coq.    (sierrensis  Ludlow). 

Aldrich,  J.  M.     Cat.  Diptera,  p.  132. 
Coquillett,  D.  W.     Can.  Ent.,  34:292-93.     1902. 
Dyar,  H.  G.     Ent.  Soc.  Wash.  Proc,  6:37-41.     1904. 

Jour.  N.  Y.  Ent.  Soc,  13  :25,  28,  54. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  97.     1905. 

8.  Ochlerotatus   lativittatus  Coq.    (curriei  Coq.). 

Aldrich,  J.  M.     Cat.  Diptera,  p.  132. 
Coquillett,  D.  W.    Can.  Ent.  33  :258-260.    1901. 
Dyar,  H.  G.     Jour.  N.  Y.  Ent.  Soc,  13:25,  54,  187. 

Ent.  Soc.  Wash.  Proc,  6:40.     1905. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  97. 

Ludlow,  C.  S.     Medical  Record,  January  20,  1906. 
Quayle,  H.  J.     Ent.  News,  Jan.,  1906. 
Theobald,  F.  V.     Monograph. 


MOSQUITO   CONTROL  WORK  IN   CALIFORNIA.  5f) 

9.  Ochlerotatus  sylvestris  Theob. 

Aldrich,  J.  M.     Cat.  Diptera,  p.  131. 

Dyae,  H.  G.     Jour.  N.  Y.  Ent..  Soc,  10:194-201.     1902. 

Jour.  N.  Y.  Ent.  Soc,  13  :24.     1905. 

Ent.   Soc.  Wash.   Proc,  5:140-148.     1903. 

Ent.  Soc.  Wash.  Proc,  6:37-41.     1904. 

Felt,  E.  P.    N.  Y.  St.  Mus.  Bull.  97. 

Ludlow,  C.  S.     Medical  Record,  January  20,  1906. 

10.  Theobaldia   incidens  Thorn,    (panticcps  Adams). 

Aldrich,  J.  M.     Cat.  Diptera,  p.  126. 

Dyar,  H.  G.     Ent.  Soc.  Wash.  Proc,  6:37-41.     1904. 

N.  Y.  Jour.  Ent.   Soc,   13 :24,   55.     1905. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  97.     1905. 
Ludlow,   C.   S.     Medical   Record,  January  20,   1906. 
Theobald,  F.  V.     Monograph  of  Culicidae. 

11.  Theobaldia  annulatus  Schran. 

Aldrich,  J.  M.     Cat.  Diptera,  p.  126. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  97. 

Osten  Sacken,  C.  R.     U.  S.  G.  &  G.  S.  Survey  Bull.  3. 

Ludlow,  C.  S.     Jour.  N.  Y.  Ent.  Soc,  10:131.     1902. 

■  Medical  Record,  January  20,  1906. 

12.  Culiseta  consobrina  Desv.    (impatiens  Walk.,  inornatus  Will.,  pinguis  Walk.). 

Aldrich,  J.  M.    Cat.  Diptera,  p.  128. 

Can.  Ent,  35  :208-210.     1903. 

Coquillett,  D.  W.     Can.  Ent.,  35:218.     1903. 
Dyar,  H.  G.     Jour.  N.  Y.  Ent.  Soc,  11:23-27.     1903. 

Ent.   Soc.   Wash.  Proc,  5  :  140-148.     1903. 

Ent.  Soc  Wash.  Proc,  6  :37-41.     1904. 

Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  79. 

N.  Y.  St.  Mus.  Bull.  97. 

Theobald,  F.  V.     Monograph. 

13.  Lepidoplatys  squamiger   Coq.    (denicdmannii   Ludlow). 

Aldrich,  J.  M.     Cat.  Diptera,  p.  131. 
Coquillett,  D.  W.     U.  S.  N.  M.  Proc,  25  :84-85. 
Dyar,  H.  G.     Jour.  N.  Y.  Ent.  Soc,  13:22,  187.     1905. 
Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  79. 
Quayle,  H.  J.     Can.  Ent.,  Jan.  1906. 
Smith,  J.  B.     N.  J.  Ex.  Sta.  Kept,  p.  221. 

14.  Psorophora  ciliata  Fabr.    (molesta  Wied.,  rubida  Desv.). 

Aldrich,  J.  M.     Cat.  Diptera,  p.   124.     1905. 
Dyar,  H.   G.     Jour.   N.   Y.   Ent.   Soc,   13:23.     1905. 
Harris,  H.  T.    Ent.  News,  14  :232-233.     1903. 
Felt,  E.  P.     N.  Y.  St.  Mus.  Bull.  79. 

•  N.  Y.  St.  Mus.  Bull.  97. 

Garman,  H.     Kentucky  Ex.  Sta.  Bull.  96. 
Giles,  G.  M.     Gnats  or  Mosquitoes,  p.  345.     1900. 
Howard,  L.  O.     Can.  Ent.,  32:353. 
Johannsen,  O.  S.     N.  Y.  St.  Mus.  Bull.  68. 
Robinson,  W.  F.     Rept.  Eliz.  N.  J.     1903. 
Theobald,  F.  V.     Monograph. 


STATION  PUBLICATIONS  AVAILABLE  FOR  DISTRIBUTION. 


REPORTS. 


1896.  Report   of    the    Viticultural    Work    during    the    seasons    1887-93,    with    data 

regarding  the  Vintages  of  1894-95. 

1897.  Resistant    Vines,    their    Selection,   Adaptation,    and   Grafting.      Appendix    to 

Viticultural  Report  for  1896. 

1898.  Partial   Report  of  Work  of  Agricultural  Experiment  Station   for  the  years 

1895-96  and  1896-97. 
1900.     Report  of  the  Agricultural  Experiment  Station  for  the  year  1897-98. 

1902.  Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 

1903.  Report  of  the  Agricultural  Experiment  Station  for  1901-1903. 

1904.  Twenty-second  Report  of  the  Agricultral  Experiment  Station  for  1903-1904. 

BULLETINS. 

Reprint.     Endurance  of  Drought  in  Soils  of  the  Arid  Region. 

No.  128.     Nature,  Value  and  Utilization  of  Alkali  Lands,  and  Tolerance  of  Alkali. 
(Revised  and  Reprint,   1905.) 

131.     The  Phylloxera  of  the  Vine. 

133.     Tolerance  of  Alkali  by  Various  Cultures. 

135.     The  Potato-Worm  in  California. 

137.  Pickling  Ripe  and  Green  Olives. 

138.  Citrus  Fruit  Culture. 

139.  Orange   and  Lemon  Rot. 

140.  Lands  of  the  Colorado  Delta  in  Salton  Basin,  and  Supplement. 

141.  Deciduous  Fruits  at  Paso  Robles. 

142.  Grasshoppers  in  California. 

143.  California  Peach-Tree  Borer. 

144.  The  Peach-Worm. 

145.  The  Red  Spider  of  Citrus  Trees. 

146.  New  Methods  of  Grafting  and  Budding  Vines. 

147.  Culture  Work  of  the  Substations. 

148.  Resistant  Vines  and  their  Hybrids. 

149.  California  Sugar  Industry. 

150.  The  Value  of  Oak  Leaves  for  Forage. 

151.  Arsenical  Insecticides. 

152.  Fumigation  Dosage. 

153.  Spraying  with  Distillates. 

154.  Sulfur  Sprays  for  Red  Spider. 

155.  Directions  for  Spraying  for  the  Codling-Moth. 

156.  Fowl  Cholera. 

157.  Commercial  Fertilizers. 

158.  California  Olive  Oil;   its  Manufacture. 

159.  Contribution  to  the  Study  of  Fermentation. 

160.  The  Hop  Aphis. 

161.  Tuberculosis   in   Fowls.      (Reprint.) 

162.  Commercial  Fertilizers.      (Dec.   1,   1904.) 

163.  Pear  Scab.  . 

164.  Poultry  Feeding  and  Proprietary  Foods.      (Reprint.) 

165.  Asparagus  and  Asparagus  Rust  in  California. 

166.  Spraying  for  Scale  Insects. 

167.  Manufacture  of  Dry  WTines  in  Hot  Countries. 

168.  Observations  on  Some  Vine  Diseases  in  Sonoma  County. 

169.  Tolerance  of  the   Sugar  Beet  for  Alkali. 

170.  Studies  in  Grasshopper  Control. 

171.  Commercial  Fertilizers.      (June  30,  1905.) 

172.  Further  Experience  in  Asparagus  Rust  Control. 

173.  Commercial  Fertilizers.      (December,  1905.) 

174.  A  New  Wine-Cooling  Machine. 

175.  Tomato   Diseases   in   California. 

176.  Sugar  Beets  in  the  San  Joaquin  Valley. 

177.  A  New  Method  of  Making  Dry  Red  Wine. 

CIRCULARS. 
No    1.     Texas  Fever.  No.  13.     The  Culture  of  the  Sugar  Beet. 

2      Blackleg.  15.     Recent  Problems  in  Agriculture. 

3!     Hog  Cholera.  What   a   University   Farm    is 

4.     Anthrax.  For. 

5*     Contagious  Abortion  in  Cows.  16.     Notes  on  Seed- Wheat. 

7      Remedies  for  Insects.  17.     Why     Agriculture     Should     be 

9      Asparagus  Rust.  Taught  in  the  Public  Schools. 

10.  Reading  Course  in  Economic  18.     Caterpillars  on  Oaks. 

Entomology.      (Revision.)  19.     Disinfection   of   Stables. 

11.  Fumigation  Practice.  20.     Reading  Course  in  Irrigation. 

12.  Silk   Culture. 

Copies  may  be  had  by  application  to  the  Director  of  the  Experiment 
Station,  Berkeley,  California. 


